vfio/pci: rename and export do_io_rw()

do_io_rw() is used to read/write to the device MMIO. The grace hopper
VFIO PCI variant driver require this functionality to read/write to
its memory.

Rename this as vfio_pci_core functions and export as GPL.

Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Yishai Hadas <yishaih@nvidia.com>
Signed-off-by: Ankit Agrawal <ankita@nvidia.com>
Link: https://lore.kernel.org/r/20240220115055.23546-2-ankita@nvidia.com


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