arm64: dts: rockchip: Add ethernet0 alias to the dts for RK3566 boards

Add ethernet0 alias to the board dts files for a few supported RK3566 boards
that had it missing.  Also, remove the ethernet0 alias from one RK3566 SoM
dtsi file, which doesn't enable the GMAC, and add the ethernet0 alias back to
the dependent board dts files, which actually enable the GMAC.

Signed-off-by: Dragan Simic <dsimic@manjaro.org>
Link: https://lore.kernel.org/r/d2a272e0ae0fff0adfab8bb0238243b11d348799.1702368023.git.dsimic@manjaro.org


Signed-off-by: Heiko Stuebner <heiko@sntech.de>