nvme-apple: Add initial Apple SoC NVMe driver

Apple SoCs such as the M1 come with an embedded NVMe controller that
is not attached to any PCIe bus. Additionally, it doesn't conform
to the NVMe specification and requires a bunch of changes to command
submission and IOMMU configuration to work.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Sven Peter <sven@svenpeter.dev>