vfio/pci: Extract duplicated code into macro

vfio_pci_core_do_io_rw() repeats the same code for multiple access
widths. Factor this out into a macro

Suggested-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Gerd Bayer <gbayer@linux.ibm.com>
Link: https://lore.kernel.org/r/20240619115847.1344875-2-gbayer@linux.ibm.com


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