vp_vdpa: switch to use vp_modern_map_vq_notify()

This patch switches to use vp_vdpa to use vp_modern_map_notify().

Signed-off-by: Jason Wang <jasowang@redhat.com>
Link: https://lore.kernel.org/r/20210415073147.19331-4-jasowang@redhat.com
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Eli Cohen <elic@nvidia.com>