[astro-thermal] Add CPU Thermal policy

- Get thermal config & opps metadata, pass it to voltage
regulator.
- Add initial thermal policy for CPU.

Test: Boot up on Astro, no functional changes needed to be tested.

Change-Id: I927b3eafb8b234e5cd0a627fac3f367283b8acf2

[astro][voltage] Add Voltage Scaling support

Added interface to get/set voltage using the PWM
This will be later used for DVFS

Test: boot up on Astro
Change-Id: I9fc6b70af399b0ac9d0bb90034f0bfd1b94c5d5d