net: stmmac: sun8i: Restore the compatibles

The original dwmac-sun8i DT bindings have some issue on how to handle
integrated PHY and was reverted in last RC of 4.13.
But now we have a solution so we need to get back that was reverted.

This patch restore compatibles about dwmac-sun8i
This reverts commit ad4540cc

 ("net: stmmac: sun8i: Remove the compatibles")

Signed-off-by: Corentin Labbe <clabbe.montjoie@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>