ext4: fix typo which causes a memory leak on error path

This was found by smatch (http://repo.or.cz/w/smatch.git/)
Signed-off-by: Dan Carpenter <error27@gmail.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Cc: stable@kernel.org

fs/ext4/mballoc.c

@@ -2699,7 +2699,7 @@ int ext4_mb_init(struct super_block *sb, int needs_recovery)
 	i = (sb->s_blocksize_bits + 2) * sizeof(unsigned int);
 	sbi->s_mb_maxs = kmalloc(i, GFP_KERNEL);
 	if (sbi->s_mb_maxs == NULL) {
-		kfree(sbi->s_mb_maxs);
+		kfree(sbi->s_mb_offsets);
 		return -ENOMEM;
 	}