arm64: dts: allwinner: a64: Add support for TERES-I laptop

The TERES-I is an open hardware laptop built by Olimex using the
Allwinner A64 SoC.

Add the board specific .dts file, which includes the A64 .dtsi and
enables the peripherals that we support so far.

Signed-off-by: Harald Geyer <harald@ccbib.org>
Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>