vfio/pci: Split linux/vfio_pci_core.h

vfio/pci: Split linux/vfio_pci_core.h

The header in include/linux should have only the exported interface for
other vfio_pci modules to use.  Internal definitions for vfio_pci.ko
should be in a "priv" header along side the .c files.

Move the internal declarations out of vfio_pci_core.h. They either move to
vfio_pci_priv.h or to the C file that is the only user.

Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Link: https://lore.kernel.org/r/1-v2-1bd95d72f298+e0e-vfio_pci_priv_jgg@nvidia.com
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>