nvme-pci: remove nvme_queue from nvme_iod

[ Upstream commit a53232cb ]

We can get the nvme_queue from the req just as easily, so remove the
duplicate path to the same structure to save some space.

Signed-off-by: Keith Busch <kbusch@kernel.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Stable-dep-of: b8f6446b ("nvme-pci: fix DMA direction of unmapping integrity data")
Signed-off-by: Sasha Levin <sashal@kernel.org>