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 <[email protected]>
diff --git a/drivers/pnp/isapnp/proc.c b/drivers/pnp/isapnp/proc.c
index 65f735a..af4d40a 100644
--- a/drivers/pnp/isapnp/proc.c
+++ b/drivers/pnp/isapnp/proc.c
@@ -55,9 +55,7 @@
 static ssize_t isapnp_proc_bus_read(struct file *file, char __user * buf,
 				    size_t nbytes, loff_t * ppos)
 {
-	struct inode *ino = file_inode(file);
-	struct proc_dir_entry *dp = PDE(ino);
-	struct pnp_dev *dev = dp->data;
+	struct pnp_dev *dev = PDE_DATA(file_inode(file));
 	int pos = *ppos;
 	int cnt, size = 256;