ARM: dts: sunxi: Raise minimum CPU voltage for sun7i-a20 to meet SoC specifications

sun7i-a20.dtsi contains a cpufreq operating point at 0.9 volts. The minimum
CPU voltage for the Allwinner A20 SoC, however, is 1.0 volts. Thus, raise
the voltage for the lowest operating point to 1.0 volts in order to stay
within the SoC specifications. It is an undervolted setting that isn't
stable across all SoCs and boards out there.

Cc: <stable@vger.kernel.org> # v4.0+
Fixes: d96b7161 ("ARM: dts: sun7i: Add cpu clock reference and operating points to dtsi")
Signed-off-by: Timo Sigurdsson <public_timo.s@silentcreek.de>
Acked-by: Iain Paton <ipaton0@gmail.com>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>