constify touch_atime()

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 9818747..65c9929 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1804,7 +1804,7 @@
 	S_VERSION = 8,
 };
 
-extern void touch_atime(struct path *);
+extern void touch_atime(const struct path *);
 static inline void file_accessed(struct file *file)
 {
 	if (!(file->f_flags & O_NOATIME))