convert nvme to atomic queue limits updates v2

[Christoph Hellwig]

Hi all,

this series converts nvme to the new atomic queue limit updates, and
as part of that refactors a lot of the setup code.  The first two
patches are block layer patches already sent out as part of the md
queue limits conversion and will hopefully get merged into Jens' tree
soon.

Changes since v1:
 - also set GENHD_FL_HIDDEN on the multipath gendisk for unknown command
   sets
 - use the queue_limits_* API for multipath device stacking
 - update the admin queue limits after reading in the MDTS value

Diffstat:
 core.c      |  393 ++++++++++++++++++++++++++++++------------------------------
 multipath.c |   13 +
 nvme.h      |   11 -
 zns.c       |   24 +--
 4 files changed, 218 insertions(+), 223 deletions(-)