net: designware: socfpga: Add ATF support for MAC driver

In non-secure mode (EL2), MAC driver calls the SMC/PSCI services
provided by ATF to setup the PHY interface.

Signed-off-by: Chee Hong Ang <chee.hong.ang@intel.com>
Signed-off-by: Siew Chin Lim <elly.siew.chin.lim@intel.com>