vfio/type1: Convert all vaddr_get_pfns() callers to use vfio_batch

This is a step towards passing the structure to vaddr_get_pfns()
directly in order to provide greater distinction between page backed
pfns and pfnmaps.

Reviewed-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Mitchell Augustin <mitchell.augustin@canonical.com>
Tested-by: Mitchell Augustin <mitchell.augustin@canonical.com>
Link: https://lore.kernel.org/r/20250218222209.1382449-3-alex.williamson@redhat.com


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