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>

fs/proc/task_nommu.c

@@ -180,7 +180,7 @@ static int nommu_vma_show(struct seq_file *m, struct vm_area_struct *vma,
 
 	if (file) {
 		seq_pad(m, ' ');
-		seq_path(m, &file->f_path, "");
+		seq_file_path(m, file, "");
 	} else if (mm) {
 		pid_t tid = pid_of_stack(priv, vma, is_pid);