UBI: rename struct ubi_scan_volume

Rename 'struct ubi_scan_volume' to 'struct ubi_ainf_volume'. This is part
of the code re-structuring I am trying to do in order to add fastmap
in a more logical way. Fastmap can share a lot with scanning, including
the attach-time data structures, which all now have "scan" word in the
name. Let's get rid of this word and use "ainf" instead which stands
for "attach information". It has the same length as "scan" so re-naming
is trivial.

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@linux.intel.com>
diff --git a/drivers/mtd/ubi/wl.c b/drivers/mtd/ubi/wl.c
index 91869e8..53ef24b 100644
--- a/drivers/mtd/ubi/wl.c
+++ b/drivers/mtd/ubi/wl.c
@@ -1384,7 +1384,7 @@
 {
 	int err, i;
 	struct rb_node *rb1, *rb2;
-	struct ubi_scan_volume *sv;
+	struct ubi_ainf_volume *sv;
 	struct ubi_ainf_peb *seb, *tmp;
 	struct ubi_wl_entry *e;