vfio/pci: Cleanup RTL8168 quirk and tracing

There's quite a bit of cleanup that can be done to the RTL8168 quirk,
as well as the tracing to prevent a spew of uninteresting accesses
for anything else the driver might choose to use the window registers
for besides the MSI-X table.  There should be no functional change,
but it's now possible to get compact and useful traces by enabling
vfio_rtl8168_quirk*, ex:

vfio_rtl8168_quirk_write 0000:04:00.0 [address]: 0x1f000
vfio_rtl8168_quirk_read 0000:04:00.0 [address]: 0x8001f000
vfio_rtl8168_quirk_read 0000:04:00.0 [data]: 0xfee0100c
vfio_rtl8168_quirk_write 0000:04:00.0 [address]: 0x1f004
vfio_rtl8168_quirk_read 0000:04:00.0 [address]: 0x8001f004
vfio_rtl8168_quirk_read 0000:04:00.0 [data]: 0x0
vfio_rtl8168_quirk_write 0000:04:00.0 [address]: 0x1f008
vfio_rtl8168_quirk_read 0000:04:00.0 [address]: 0x8001f008
vfio_rtl8168_quirk_read 0000:04:00.0 [data]: 0x49b1
vfio_rtl8168_quirk_write 0000:04:00.0 [address]: 0x1f00c
vfio_rtl8168_quirk_read 0000:04:00.0 [address]: 0x8001f00c
vfio_rtl8168_quirk_read 0000:04:00.0 [data]: 0x0

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
