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/gpu/drm/drm_proc.c b/drivers/gpu/drm/drm_proc.c
index ff5456b..e064318 100644
--- a/drivers/gpu/drm/drm_proc.c
+++ b/drivers/gpu/drm/drm_proc.c
@@ -63,7 +63,7 @@
 
 static int drm_proc_open(struct inode *inode, struct file *file)
 {
-	struct drm_info_node* node = PDE(inode)->data;
+	struct drm_info_node* node = PDE_DATA(inode);
 
 	return single_open(file, node->info_ent->show, node);
 }