ext2: fix return of uninitialised variable

gcc correctly says

fs/ext2/super.c: In function 'ext2_remount':
fs/ext2/super.c:1055: warning: 'err' may be used uninitialized in this function
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/ext2/super.c

@@ -1043,6 +1043,7 @@ static int ext2_remount (struct super_block * sb, int * flags, char * data)
 
 	if ((ext2_use_xip(sb)) && (sb->s_blocksize != PAGE_SIZE)) {
 		printk("XIP: Unsupported blocksize\n");
+		err = -EINVAL;
 		goto restore_opts;
 	}