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/gadget/rndis.c b/drivers/usb/gadget/rndis.c
index d9297ee..1e4cfb0 100644
--- a/drivers/usb/gadget/rndis.c
+++ b/drivers/usb/gadget/rndis.c
@@ -1065,7 +1065,7 @@
 static ssize_t rndis_proc_write(struct file *file, const char __user *buffer,
 				size_t count, loff_t *ppos)
 {
-	rndis_params *p = PDE(file_inode(file))->data;
+	rndis_params *p = PDE_DATA(file_inode(file));
 	u32 speed = 0;
 	int i, fl_speed = 0;
 
@@ -1109,7 +1109,7 @@
 
 static int rndis_proc_open(struct inode *inode, struct file *file)
 {
-	return single_open(file, rndis_proc_show, PDE(inode)->data);
+	return single_open(file, rndis_proc_show, PDE_DATA(inode));
 }
 
 static const struct file_operations rndis_proc_fops = {