[PATCH 1/4] nvme: move driver into subdirectory

[Cayton, Phil]

> So, why not drivers/nvme/host?  As said I'm not dead set on the host 
> name, but having a drivers/nvme sounds useful with all the additional 
> nvme-related code we're going to get soon.

Two questions:
1. Since this is the block driver for NVMe why would we not put this under block (e.g., drivers/block/nvme)
2. Are we assuming any target code will go in this path as well?  Why would not any target code go under drivers/target?