ARM: dts: sunxi: h3-h5: Add Bananapi M2+ v1.2 device trees

Bananapi released an updated revision of the H3/H5 based Bananapi M2+.
Version 1.2 enables voltage control for the CPU's regulator by using
a GPIO line to toggle a MOSFET that can change the effective resistance
value in the regulator's feedback network.

This patch adds a common .dtsi file for this new revision, which
includes the original common sunxi-bananapi-m2-plus.dtsi file, and
adds the GPIO-controlled regulator and a cpu-supply reference. H3
and H5 variant dts files are added as well.

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