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>

ipc/util.c

@@ -964,7 +964,7 @@ static int sysvipc_proc_open(struct inode *inode, struct file *file)
 	seq = file->private_data;
 	seq->private = iter;
 
-	iter->iface = PDE(inode)->data;
+	iter->iface = PDE_DATA(inode);
 	iter->ns    = get_ipc_ns(current->nsproxy->ipc_ns);
 out:
 	return ret;