blk-mq: inline hot part of __blk_mq_sched_restart

Extract a fast check out of __block_mq_sched_restart() and inline it for
performance reasons.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/894abaa0998e5999f2fe18f271e5efdfc2c32bd2.1633781740.git.asml.silence@gmail.com


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