power: introduce 8974-specific handling

When the display turns off, the MSM8974
needs to set ondemand governor's sync_freq
and optimal_freq parameters to values different
from other targets. To accomplish this, override
the handling for set_interactive. Also refactor
power HAL to remove unnecessary macros.

Change-Id: I009ee88886abfb4f8423de3b2d85549fd0e65205
7 files changed