nvme: fold nvme_config_discard() into nvme_update_disk_info()

nvme: fold nvme_config_discard() into nvme_update_disk_info()

The choice of what queue limits are set in nvme_update_disk_info() vs.
nvme_config_discard() seems a bit arbitrary. A subsequent commit will
compute the discard_granularity limit using struct nvme_id_ns, which is
only passed to nvme_update_disk_info() currently. So move the logic in
nvme_config_discard() to nvme_update_disk_info(). Replace several
instances of ns->ctrl in nvme_update_disk_info() with the ctrl variable
brought from nvme_config_discard().

Signed-off-by: Caleb Sander Mateos <csander@purestorage.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Keith Busch <kbusch@kernel.org>