ext4: remove redundant mb_regenerate_buddy()

After this patch (163a203d), if an abnormal bitmap is detected, we
will mark the group as corrupt, and we will not use this group in
the future. Therefore, it should be meaningless to regenerate the
buddy bitmap of this group, It might be better to delete it.

Signed-off-by: Chunguang Xu <brookxu@tencent.com>
Reviewed-by: Andreas Dilger <adilger@dilger.ca>
Link: https://lore.kernel.org/r/1604764698-4269-2-git-send-email-brookxu@tencent.com


Signed-off-by: Theodore Ts'o <tytso@mit.edu>