vfio: move hw/misc/vfio.c to hw/vfio/pci.c Move vfio.h into include/hw/vfio

This is done in preparation for the addition of VFIO platform
device support.

Signed-off-by: Kim Phillips <kim.phillips@linaro.org>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>