nvme: return the whole CQE through the request passthrough interface

Both LighNVM and NVMe over Fabrics need to look at more than just the
status and result field.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Matias Bj?rling <m@bjorling.me>
Reviewed-by: Jay Freyensee <james.p.freyensee@intel.com>
Reviewed-by: Sagi Grimberg <sagig@mellanox.com>
Signed-off-by: Sagi Grimberg <sagig@mellanox.com>
Reviewed-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Jens Axboe <axboe@fb.com>