ARM: dts: sun8i-h2-plus-bananapi-m2-zero: add regulator nodes vcc-dram and vcc1v2

Add regulator nodes vcc-dram and vcc1v2 to the devicetree. These
regulators correspond to U4 and U5 in the schematics:

http://forum.banana-pi.org/t/bpi-m2-zero-schematic-diagram-public/4111



Signed-off-by: Michael Klein <michael@fossekall.de>
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Link: https://lore.kernel.org/r/20201130183841.136708-1-michael@fossekall.de