blk-mq: make sure active queue usage is held for bio_integrity_prep()

In the Linux kernel, the following vulnerability has been resolved: blk-mq: make sure active queue usage is held for bio_integrity_prep() blk_integrity_unregister() can come if queue usage counter isn't held for one bio with integrity prepared, so this request may be completed with calling profile->complete_fn, then kernel panic. Another constraint is that bio_integrity_prep() needs to be called before bio merge. Fix the issue by: - call bio_integrity_prep() with one queue usage counter grabbed reliably - call bio_integrity_prep() before bio merge