sunxi: enable H3 EMAC for the nanopi neo

The nanopi already had the CONFIG_SUN8I_EMAC=y enabled in it's defconfig
file, but was missing the &emac the device tree entry.

Signed-off-by: Jelle van der Waa <jelle@vdwaa.nl>
Acked-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Reviewed-by: Jagan Teki <jagan@openedev.com>