nvme-pci: Add support for Apple 2018+ models

Based on reverse engineering and original patch by

Paul Pawlowski <paul@mrarm.io>

This adds support for Apple weird implementation of NVME in their
2018 or later machines. It accounts for the twice-as-big SQ entries
for the IO queues, and the fact that only interrupt vector 0 appears
to function properly.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Reviewed-by: Minwoo Im <minwoo.im.dev@gmail.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Sagi Grimberg <sagi@grimberg.me>