ARM: dts: sun8i: a83t: cubietruck-plus: Add AXP818 regulator nodes

This patch adds device nodes for all the regulators of the AXP818 PMIC.
Sunxi common regulators are removed, and USB VBUS regulators are added.

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