sunxi: DT: A64: update board .dts files from Linux

Update the .dts files for the various boards with an Allwinner A64 SoC.
This is as of v4.18-rc3, exactly Linux commit:
commit 818668055c9d588c9a9d151e3b258ed1adacba0b
Author: Jagan Teki <jagan@amarulasolutions.com>
Date:   Mon Apr 23 12:02:39 2018 +0530

    arm64: dts: allwinner: a64: bananapi-m64: add usb otg

It updates the existing DT files, adds the newly added axp803.dtsi and
removes our temporary kludge file to get Ethernet support in U-Boot.
I left the amarula-relic alone, as this DT has not reached mainline yet.
The changes are not critical anyway, and the next sync will fix this.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Acked-by: Maxime Ripard <maxime.ripard@bootlin.com>
Acked-by: Jagan Teki <jagan@amarulasolutions.com>
Tested-by: Jagan Teki <jagan@amarulasolutions.com>