FROMGIT: bfq/mq-deadline: remove redundant check for passthrough request

Since commit 01e99aec 'blk-mq: insert passthrough request into
hctx->dispatch directly', passthrough request should not appear in
IO-scheduler any more, so blk_rq_is_passthrough checking in addon IO
schedulers is redundant.

(Notes: this patch passes generic IO load test with hdds under SAS
controller and hdds under AHCI controller but obviously not covers all.
Not sure if passthrough request can still escape into IO scheduler from
blk_mq_sched_insert_requests, which is used by blk_mq_flush_plug_list and
has lots of indirect callers.)

Signed-off-by: Lin Feng <linf@wangsu.com>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
BUG: 187357408
Change-Id: I97d85c38e584add44399295f3839994b694bc9ca
(cherry picked from commit 0856faaa220759a4fe4334f5c57a8661c94c14ce git://git.kernel.dk/linux-block/

 for-5.14/block)
Signed-off-by: Bart Van Assche <bvanassche@google.com>