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/drivers/usb/host/sl811-hcd.c b/drivers/usb/host/sl811-hcd.c
index d62f040..313d0bb 100644
--- a/drivers/usb/host/sl811-hcd.c
+++ b/drivers/usb/host/sl811-hcd.c
@@ -1494,7 +1494,7 @@
 
 static int proc_sl811h_open(struct inode *inode, struct file *file)
 {
-	return single_open(file, proc_sl811h_show, PDE(inode)->data);
+	return single_open(file, proc_sl811h_show, PDE_DATA(inode));
 }
 
 static const struct file_operations proc_ops = {