vdpa_sim: filter destination mac address

This patch implements a simple unicast filter for vDPA simulator.

Signed-off-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Gautam Dawar <gdawar@xilinx.com>
Message-Id: <20220330180436.24644-19-gdawar@xilinx.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>