blk-mq: unshared timeout handler

Duplicate the (small) timeout handler in blk-mq so that we can pass
arguments more easily to the driver timeout handler.  This enables
the next patch.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>

diff --cc block/blk-mq.c
Simple merge

diff --cc block/blk-timeout.c
Simple merge

diff --cc block/blk.h
Simple merge