vdpa_sim_net: Make mac address array static

MAC address array is used only in vdpa_sim_net.c.
Hence, keep it static.

Signed-off-by: Parav Pandit <parav@nvidia.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Link: https://lore.kernel.org/r/20210105103203.82508-2-parav@nvidia.com


Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>