fix discard limits

[Christoph Hellwig]

Hi all,

this series fixes a few issues related to max_discard_sector limits
in the block layer and nvme.

Subject:
 block/blk-settings.c     |    4 +++-
 drivers/nvme/host/core.c |   35 +++++++++++++----------------------
 drivers/nvme/host/nvme.h |    3 +--
 3 files changed, 17 insertions(+), 25 deletions(-)