net/null: add MAC address setting fake operation
net/null: add MAC address setting fake operation

Needed if used with net/bonding

Signed-off-by: Radu Nicolau <fa459cf59d47c122ba776e9a6f631c862bf44680@intel.com>
Reviewed-by: Ferruh Yigit <ba8734c3c506d2e3557bd4ac8fdaccd25bdb9aa7@intel.com>

john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk