ext3: drop if around WARN_ON

Just use WARN_ON rather than an if containing only WARN_ON(1).

A simplified version of the semantic patch that makes this transformation
is as follows: (http://coccinelle.lip6.fr/)

// <smpl>
@@
expression e;
@@
- if (e) WARN_ON(1);
+ WARN_ON(e);
// </smpl>
Signed-off-by: Julia Lawall <Julia.Lawall@lip6.fr>
Signed-off-by: Jan Kara <jack@suse.cz>

fs/ext3/inode.c

@@ -1071,8 +1071,7 @@ struct buffer_head *ext3_getblk(handle_t *handle, struct inode *inode,
 	 * mapped. 0 in case of a HOLE.
 	 */
 	if (err > 0) {
-		if (err > 1)
-			WARN_ON(1);
+		WARN_ON(err > 1);
 		err = 0;
 	}
 	*errp = err;