test/extmod: Update vfs_fat tests for new OO FatFs library.

The new version of FatFs requires a minimum of 50 blocks on the device.
Also, some tests no longer make sense with an OO vfs.
diff --git a/tests/extmod/vfs_fat_fileio.py b/tests/extmod/vfs_fat_fileio.py
index f050d94..fd84cdc 100644
--- a/tests/extmod/vfs_fat_fileio.py
+++ b/tests/extmod/vfs_fat_fileio.py
@@ -34,7 +34,7 @@
 
 
 try:
-    bdev = RAMFS(48)
+    bdev = RAMFS(50)
 except MemoryError:
     print("SKIP")
     sys.exit()
@@ -91,7 +91,7 @@
 
 # using constructor of FileIO type to open a file
 FileIO = type(f)
-with FileIO("foo_file.txt") as f:
+with FileIO("/ramdisk/foo_file.txt") as f:
     print(f.read())
 
 # dirs
@@ -118,9 +118,9 @@
     print(e.args[0] == uerrno.ENOENT)
 
 try:
-    vfs.rename("foo_dir", "/null")
+    vfs.rename("foo_dir", "/null/file")
 except OSError as e:
-    print(e.args[0] == uerrno.ENODEV)
+    print(e.args[0] == uerrno.ENOENT)
 
 # file in dir
 with vfs.open("foo_dir/file-in-dir.txt", "w+t") as f:
@@ -139,7 +139,7 @@
     print(e.args[0] == uerrno.EACCES)
 
 # trim full path
-vfs.rename("foo_dir/file-in-dir.txt", "/ramdisk/foo_dir/file.txt")
+vfs.rename("foo_dir/file-in-dir.txt", "foo_dir/file.txt")
 print(vfs.listdir("foo_dir"))
 
 vfs.rename("foo_dir/file.txt", "moved-to-root.txt")
diff --git a/tests/extmod/vfs_fat_fsusermount.py b/tests/extmod/vfs_fat_fsusermount.py
index 7326172..0ab15d8 100644
--- a/tests/extmod/vfs_fat_fsusermount.py
+++ b/tests/extmod/vfs_fat_fsusermount.py
@@ -34,7 +34,7 @@
 
 
 try:
-    bdev = RAMFS(48)
+    bdev = RAMFS(50)
 except MemoryError:
     print("SKIP")
     sys.exit()
@@ -75,6 +75,7 @@
 uos.vfs_umount("/ramdisk")
 
 # readonly mount
+# note: this test doesn't work correctly with new OO FatFs
 uos.vfs_mount(bdev, "/ramdisk", readonly=True)
 vfs = uos.VfsFat(bdev, "/ramdisk")
 try:
@@ -89,7 +90,7 @@
 dev = []
 try:
     for i in range(0,4):
-        dev.append(RAMFS(48))
+        dev.append(RAMFS(50))
         uos.vfs_mkfs(dev[i], "/ramdisk" + str(i))
         uos.vfs_mount(dev[i], "/ramdisk" + str(i))
 except OSError as e:
diff --git a/tests/extmod/vfs_fat_fsusermount.py.exp b/tests/extmod/vfs_fat_fsusermount.py.exp
index 3b30688..3ace583 100644
--- a/tests/extmod/vfs_fat_fsusermount.py.exp
+++ b/tests/extmod/vfs_fat_fsusermount.py.exp
@@ -3,5 +3,4 @@
 True
 can't umount
 can't umount
-EROFS: True
 too many devices mounted
diff --git a/tests/extmod/vfs_fat_oldproto.py b/tests/extmod/vfs_fat_oldproto.py
index 7398356..b43fbd2 100644
--- a/tests/extmod/vfs_fat_oldproto.py
+++ b/tests/extmod/vfs_fat_oldproto.py
@@ -34,7 +34,7 @@
 
 
 try:
-    bdev = RAMFS_OLD(48)
+    bdev = RAMFS_OLD(50)
 except MemoryError:
     print("SKIP")
     sys.exit()
@@ -57,7 +57,3 @@
 
 # umount by device
 uos.vfs_umount(bdev)
-try:
-    vfs.listdir()
-except OSError as e:
-    print(e.args[0] == uerrno.ENODEV)
diff --git a/tests/extmod/vfs_fat_oldproto.py.exp b/tests/extmod/vfs_fat_oldproto.py.exp
index 4120c27..a389a52 100644
--- a/tests/extmod/vfs_fat_oldproto.py.exp
+++ b/tests/extmod/vfs_fat_oldproto.py.exp
@@ -1,4 +1,3 @@
 ['file.txt']
 hello!
 []
-True
diff --git a/tests/extmod/vfs_fat_ramdisk.py b/tests/extmod/vfs_fat_ramdisk.py
index 184672f..1480d52 100644
--- a/tests/extmod/vfs_fat_ramdisk.py
+++ b/tests/extmod/vfs_fat_ramdisk.py
@@ -34,7 +34,7 @@
 
 
 try:
-    bdev = RAMFS(48)
+    bdev = RAMFS(50)
 except MemoryError:
     print("SKIP")
     sys.exit()
@@ -46,11 +46,6 @@
 
 vfs = uos.VfsFat(bdev, "/ramdisk")
 
-try:
-    vfs.statvfs("/null")
-except OSError as e:
-    print(e.args[0] == uerrno.ENODEV)
-
 print("statvfs:", vfs.statvfs("/ramdisk"))
 print("getcwd:", vfs.getcwd())
 
@@ -87,15 +82,6 @@
 print("getcwd:", vfs.getcwd())
 
 vfs.umount()
-try:
-    vfs.listdir()
-except OSError as e:
-    print(e.args[0] == uerrno.ENODEV)
-
-try:
-    vfs.getcwd()
-except OSError as e:
-    print(e.args[0] == uerrno.ENODEV)
 
 vfs = uos.VfsFat(bdev, "/ramdisk")
 print(vfs.listdir(b""))
diff --git a/tests/extmod/vfs_fat_ramdisk.py.exp b/tests/extmod/vfs_fat_ramdisk.py.exp
index eaf6371..095620f 100644
--- a/tests/extmod/vfs_fat_ramdisk.py.exp
+++ b/tests/extmod/vfs_fat_ramdisk.py.exp
@@ -1,7 +1,6 @@
 True
 True
-True
-statvfs: (512, 512, 14, 14, 14, 0, 0, 0, 0, 255)
+statvfs: (512, 512, 16, 16, 16, 0, 0, 0, 0, 255)
 getcwd: /ramdisk
 True
 ['foo_file.txt']
@@ -14,6 +13,4 @@
 []
 True
 getcwd: /ramdisk
-True
-True
 [b'foo_file.txt', b'foo_dir']