The Cubietruck has an AXP209 PMIC and can be power-supplied by ACIN via
 the CHG-IN pin or by USB.

This enables the ACIN and the USB power supply subnode in the DT.
Signed-off-by: Alexander Syring <alex@asyring.de>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>