provide nvme_ops for vanilla pci nvme, and use them in the right places.

provide nvme_ops for vanilla pci nvme, and use them in the right places.

this paves the way for supporting the apple nvme storage controllers.
hopefully most of the remaining work on that is in the bus glue for
those controllers and this code won't need more tweaks.

hibernate still works, but it's relying on luck at the moment.
hibernate on arm64 and the apple controllers in particular will
almost certainly require more work here.

ok jmatthew@