arm64: dts: allwinner: Revert EMAC changes

Since the discussion is not settled yet for the EMAC, and that the release
in getting really close, let's revert the changes for now, and we'll
reintroduce them later.

Acked-by: Chen-Yu Tsai <wens@csie.org>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>