sunxi: a527: radxa/avaota: enable Ethernet

sunxi: a527: radxa/avaota: enable Ethernet

The first of the two Ethernet controllers in the Allwinner A527/T527 is
compatible to the MAC from the previous SoCs. Consequently the recent DT
update brought use the MAC node, using the A64 compatible string as the
fallback, which works out of the box.

Enable the sun8i-emac Ethernet driver in the defconfig for the Radxa and
the Avaota boards, so that kernels and other data can be loaded via
TFTP. Please note that only one of the Ethernet sockets will work, the
second MAC is not compatible, and needs a new U-Boot driver. The
X96QPro+ TV box unfortunately uses only this second EMAC, so Ethernet
cannot be used there at the moment.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Reviewed-by: Jernej Skrabec <jernej.skrabec@gmail.com>