Although these should have been 'emac', upstream DTS is going with using
'gmac' as the function name for the emac RGMII pins. Rename here to
accommodate.
emac support for the a83t should come in with the 4.16 DTS update, in
another couple of months.
Clocks, GPIO, UART, SD card / eMMC, USB, watchdog, and ethernet are
supported. Note that the A83T contains two clusters of four Cortex-A7
CPUs, and only CPUs in first cluster are started for now.
Tested on a Sinovoip Banana Pi BPI-M3.