boards: atsame54_xpro add support for PHY driver
boards: atsame54_xpro add support for PHY driver

Update to dts file to use the generic MII PHY driver.

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

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