The CPU on Allwinner H3 can do dynamic frequency scaling.

Add a DVFS table based on the one shipped with Allwinner's H3 SDK. The
voltage-frequency relationship seems to be conservative, and Armbian has
another DVFS table which uses lower voltage at a certain frequency.
However, the official one is chosen for safety.

Frequencies higher than 1008MHz are temporarily dropped in the table, as
they may lead to over voltage on boards without proper regulator
settings or over temperature on boards with proper regulator settings.
They will be added back once regulator settings are ready and thermal
sensor driver is merged.

In order to satisfy all different regulators (SY8106A which is 50mV per
level, SY8113B which have two states: 1.1V and 1.3V, and some board with
non-tweakable regulators), all the OPPs are defined with a range which has
the target value as the minimum allowed value, and 1.3V (the highest
VDD-CPUX voltage suggested by the datasheet) as the maximum allowed value.
It's proven to work well with a board with SY8113B.
Signed-off-by: Icenowy Zheng <icenowy@aosc.io>
Signed-off-by: Chen-Yu Tsai <wens@csie.org>