ext4: remove unnecessary code in __mb_check_buddy

When enter elseif branch, the the MB_CHECK_ASSERT will never fail.
In addtion, the only illegal combination is 0/0, which can be caught
by the first if branch.
Signed-off-by: NJinke Han <hanjinke.666@bytedance.com>
Reviewed-by: NJan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20220404152243.13556-1-hanjinke.666@bytedance.comSigned-off-by: NTheodore Ts'o <tytso@mit.edu>

fs/ext4/mballoc.c

@@ -695,13 +695,10 @@ static int __mb_check_buddy(struct ext4_buddy *e4b, char *file,
 		for (i = 0; i < max; i++) {
 
 			if (mb_test_bit(i, buddy)) {
-				/* only single bit in buddy2 may be 1 */
+				/* only single bit in buddy2 may be 0 */
 				if (!mb_test_bit(i << 1, buddy2)) {
 					MB_CHECK_ASSERT(
 						mb_test_bit((i<<1)+1, buddy2));
-				} else if (!mb_test_bit((i << 1) + 1, buddy2)) {
-					MB_CHECK_ASSERT(
-						mb_test_bit(i << 1, buddy2));
 				}
 				continue;
 			}