[PATCH] Move nvme driver source into subdirectory and move pci specifics from core into separate file

[hch@infradead.org (Christoph Hellwig)]

Hi J,

thanks for starting this important work, but I think we need to do
this in smaller steps.  This large patch does a few things at the same
time:

 - move files to a new directory
 - split data structures
 - split files
 - introduces a new internal API

Which need to be split over a few patches.  I'd suggest we start with
the easiest and most important parts first and then iterate through the
rest.

My suggestion would be:

 a) move files to a new directory.  My suggestion for that would be
    driver/nvme/host/ as I have a software NVMe controller
    implementation under development which I'd like to also add under
    a different subdirectory of drivers/nvme.
 b) start splitting struct nvme_dev into a generic struct nvme_ctrl
    and a PCI-specific nvme_pci_ctrl

Based on that we can start thinking about an API and move the PCI code
to it's own file.  Note that most of your operations should not be
needed.  With my ongoing work we now have the nvme_submit*cmd* APIs
that give a nice separatation for anything related to NVMe commans,
so we'd just need abstractions for the BAR access.