blk-mq: pass a reserved argument to the timeout handler

Allow blk-mq to pass an argument to the timeout handler to indicate
if we're timing out a reserved or regular command.  For many drivers
those need to be handled different.

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 drivers/scsi/scsi_lib.c
Simple merge

diff --cc include/linux/blk-mq.h
Simple merge