procfs: new helper - PDE_DATA(inode)

The only part of proc_dir_entry the code outside of fs/proc
really cares about is PDE(inode)->data.  Provide a helper
for that; static inline for now, eventually will be moved
to fs/proc, along with the knowledge of struct proc_dir_entry
layout.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/net/core/pktgen.c b/net/core/pktgen.c
index 6048fc1..f6af4fe 100644
--- a/net/core/pktgen.c
+++ b/net/core/pktgen.c
@@ -508,7 +508,7 @@
 
 static int pgctrl_open(struct inode *inode, struct file *file)
 {
-	return single_open(file, pgctrl_show, PDE(inode)->data);
+	return single_open(file, pgctrl_show, PDE_DATA(inode));
 }
 
 static const struct file_operations pktgen_fops = {
@@ -1685,7 +1685,7 @@
 
 static int pktgen_if_open(struct inode *inode, struct file *file)
 {
-	return single_open(file, pktgen_if_show, PDE(inode)->data);
+	return single_open(file, pktgen_if_show, PDE_DATA(inode));
 }
 
 static const struct file_operations pktgen_if_fops = {
@@ -1823,7 +1823,7 @@
 
 static int pktgen_thread_open(struct inode *inode, struct file *file)
 {
-	return single_open(file, pktgen_thread_show, PDE(inode)->data);
+	return single_open(file, pktgen_thread_show, PDE_DATA(inode));
 }
 
 static const struct file_operations pktgen_thread_fops = {