arm64: dts: meson: add common SM1 ac2xx dtsi

Add a common dtsi for Android STB devices based on the Amlogic S905X3
(AC213/AC214) and S905D3 (AC201/AC202) reference designs. The dtsi is
loosely based on the existing SEI610 device-tree.

Signed-off-by: Christian Hewitt <christianshewitt@gmail.com>
Tested-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com> # X96-Air with Gbit PHY
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Link: https://lore.kernel.org/r/20220112022713.25962-2-christianshewitt@gmail.com