dm rq: don't queue request to blk-mq during DM suspend

In the Linux kernel, the following vulnerability has been resolved:

dm rq: don't queue request to blk-mq during DM suspend

DM uses blk-mq's quiesce/unquiesce to stop/start device mapper queue.

But blk-mq's unquiesce may come from outside events, such as elevator

switch, updating nr_requests or others, and request may come during

suspend, so simply ask for blk-mq to requeue it.

Fixes one kernel panic issue when running updating nr_requests and

dm-mpath suspend/resume stress test.