nvme-pci: cleaning up nvme_pci_init_request

Erase the superfluous line that retrieves the nvme_dev.

Signed-off-by: Irvin Cote <irvincoteg@gmail.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Keith Busch <kbusch@kernel.org>