Merge tag 'v3.15-rc1' into for-3.16/core

We don't like this, but things have diverged with the blk-mq fixes
in 3.15-rc1. So merge it in.

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

diff --cc drivers/scsi/scsi_lib.c
Simple merge

diff --cc include/linux/blkdev.h
Simple merge