ARM: dts: sunxi: bananapi-m2-plus-v1.2: Fix CPU supply voltages

The Bananapi M2+ uses a GPIO line to change the effective resistance of
the CPU supply regulator's feedback resistor network. The voltages
described in the device tree were given directly by the vendor. This
turns out to be slightly off compared to the real values.

The updated voltages are based on calculations of the feedback resistor
network, and verified down to three decimal places with a multi-meter.

Fixes: 6eeb4180 ("ARM: dts: sunxi: h3-h5: Add Bananapi M2+ v1.2 device trees")
Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Link: https://lore.kernel.org/r/20200717160053.31191-4-wens@kernel.org