vdpa_sim_net: should not drop the multicast/broadcast packet

In the receive_filter(), should not drop the packet with the
broadcast/multicast address. Add the check for this

Signed-off-by: Cindy Lu <lulu@redhat.com>
Message-Id: <20221214054306.24145-1-lulu@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>