vfs: add seq_file_path() helper

Turn
	seq_path(..., &file->f_path, ...);
into
	seq_file_path(..., file, ...);

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/proc/nommu.c b/fs/proc/nommu.c
index d4a3574..f8595e8 100644
--- a/fs/proc/nommu.c
+++ b/fs/proc/nommu.c
@@ -64,7 +64,7 @@
 
 	if (file) {
 		seq_pad(m, ' ');
-		seq_path(m, &file->f_path, "");
+		seq_file_path(m, file, "");
 	}
 
 	seq_putc(m, '\n');