vfio: Move the PCI implementation to the PCI crate

There is a much stronger PCI dependency from vfio_pci.rs than a VFIO one
from pci/src/vfio.rs. It seems more natural to have the PCI specific
VFIO implementation in the PCI crate rather than the other way around.

Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

Cargo.lock

@@ -683,15 +683,20 @@ dependencies = [
  "anyhow",
  "byteorder",
  "devices",
+ "kvm-bindings",
+ "kvm-ioctls",
  "libc",
  "log 0.4.8",
  "serde",
  "serde_derive",
  "serde_json",
+ "vfio",
+ "vfio-bindings",
  "vm-allocator",
  "vm-device",
  "vm-memory",
  "vm-migration",
+ "vmm-sys-util",
 ]
 
 [[package]]
@@ -1345,14 +1350,11 @@ version = "0.0.1"
 dependencies = [
  "arc-swap",
  "byteorder",
- "devices",
  "kvm-bindings",
  "kvm-ioctls",
  "libc",
  "log 0.4.8",
- "pci",
  "vfio-bindings",
- "vm-allocator",
  "vm-device",
  "vm-memory",
  "vmm-sys-util",