vfio/pci : Add pba_offset PCI quirk for Chelsio T5 devices

Fix pba_offset initialization value for Chelsio T5 Virtual Function
device. The T5 hardware has a bug in it where it reports a Pending Interrupt
Bit Array Offset of 0x8000 for its SR-IOV Virtual Functions instead
of the 0x1000 that the hardware actually uses internally. As the hardware
doesn't return the correct pba_offset value, add a quirk to instead
return a hardcoded value of 0x1000 when a Chelsio T5 VF device is
detected.

This bug has been fixed in the Chelsio's next chip series T6 but there are
no plans to respin the T5 ASIC for this bug. It is just documented in the
T5 Errata and left it at that.

Signed-off-by: Gabriel Laupre <glaupre@chelsio.com>
Reviewed-by: Bandan Das <bsd@redhat.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>