block: remove unnecessary check in blk_unfreeze_check_owner()

The following check of 'q->mq_freeze_owner != current' covers the
previous one, so remove the unnecessary check.

Signed-off-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20241127135133.3952153-2-ming.lei@redhat.com


Signed-off-by: Jens Axboe <axboe@kernel.dk>