ensure each gendisk always has a request_queue reference

[Christoph Hellwig]

Hi Jens,

this is the final batch of the gendisk interface cleanup series.  This
remove the last uses of the legacy alloc_disk interface and ensures we
always have a request_queue reference for a gendisk.

Diffstat:
 block/blk-mq.c                  |    6 ++--
 block/genhd.c                   |   31 ++++++++++---------------
 drivers/nvme/host/core.c        |   33 ++++++++++----------------
 drivers/s390/block/dasd_genhd.c |    7 ++++-
 drivers/scsi/sd.c               |    6 +++-
 drivers/scsi/sg.c               |   32 +++++++-------------------
 drivers/scsi/sr.c               |    7 ++++-
 drivers/scsi/st.c               |   49 +++++++++-------------------------------
 drivers/scsi/st.h               |    2 -
 include/linux/blk-mq.h          |   10 ++------
 include/linux/genhd.h           |   30 +++---------------------
 11 files changed, 72 insertions(+), 141 deletions(-)