power: Clean up and fix video encode/decode hint handling

* Unify code style for non legacy SoCs
* Restore legacy SoC handling which used to live in power-common.c
  but was removed in commit 561cffcbfa66192e839e040d2da3bff2ecf8dcac

Change-Id: Ieb84e6d6c8d762614e21267e81e6057aa64b36dd
17 files changed