net: ethernet: ave: Add compatible string and SoC-dependent data for NX1 SoC

Add basic support for UniPhier NX1 SoC. This includes a compatible string
and SoC-dependent data.

Signed-off-by: Kunihiko Hayashi <hayashi.kunihiko@socionext.com>
Signed-off-by: David S. Miller <davem@davemloft.net>