vfio-pci: Add extra debugging

Often when debugging it's useful to be able to disable bypass paths
so no interactions with the device are missed.  Add some extra debug
options to do this.  Also add device info on read/write BAR accesses,
which is useful when debugging more than one assigned device.  A
couple DPRINTFs also had redundant "vfio:" prefixes.

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