drivers: ethernet: eth_sam_gmac: allow changing mac address
drivers: ethernet: eth_sam_gmac: allow changing mac address

Support setting MAC address manually at runtime for Atmel SAM Ethernet
driver. The MAC address can be set using an ethernet management
request, e.g. (`net_mgmt(NET_REQUEST_ETHERNET_SET_MAC_ADDRESS, ...)`).

Signed-off-by: Arvin Farahmand <4208c8ae77e6dd3ecebee6cbd1512b26823ef0ce@ip-logix.com>

nashif/zephyr,Vudentz/zephyr,galak/zephyr,galak/zephyr,zephyrproject-rtos/zephyr,zephyrproject-rtos/zephyr,Vudentz/zephyr,finikorg/zephyr,finikorg/zephyr,finikorg/zephyr,nashif/zephyr,finikorg/zephyr,galak/zephyr,galak/zephyr,zephyrproject-rtos/zephyr,nashif/zephyr,Vudentz/zephyr,galak/zephyr,Vudentz/zephyr,Vudentz/zephyr,Vudentz/zephyr,finikorg/zephyr,zephyrproject-rtos/zephyr,nashif/zephyr,zephyrproject-rtos/zephyr,nashif/zephyr