pds_core: Require callers of register/unregister to pass PF drvdata

Pass a pointer to the PF's private data structure rather than
bouncing in and out of the PF's PCI function address.

Signed-off-by: Shannon Nelson <shannon.nelson@amd.com>
Signed-off-by: Brett Creeley <brett.creeley@amd.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Shameer Kolothum <shameerali.kolothum.thodi@huawei.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/20230807205755.29579-4-brett.creeley@amd.com
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>