arm64: allwinner: h6: add EMAC device nodes

Allwinner H6 SoC has an EMAC like the one in A64.

Add device tree nodes for the H6 DTSI file.

Signed-off-by: Icenowy Zheng <icenowy@aosc.io>
Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>