nvme: Use kernel private memory barriers

Change-Id: I1747de7afb2a5b2ec845c1c14f013dbcb9bd72f8
Reviewed-on: https://review.haiku-os.org/c/1528
Reviewed-by: Alex von Gluck IV <kallisti5@unixzen.com>
Reviewed-by: Adrien Destugues <pulkomandy@gmail.com>
Reviewed-by: Axel Dörfler <axeld@pinc-software.de>

nvme: Fix nvme driver build on non-x86

Change-Id: Ia7a1dc56bcec69678e1fc2d8a427c24a32215bb8

nvme: Import glue code to our PCI and VM APIs.

Largely simple and painless, thanks to libnvme's abstractions.