power: keep two cores online when display is on

This change is specific to 8084 and has been
modeled based on 8974 pro changes. Use PerfLock
to keep two cores online when the display is on.

Change-Id: Iffea0f9afbb3743cec2804da5884ec6d977b662a
power: Add apq8084 specific changes

Added compilation flag for power-8084.c in
makefile and detection of apq8084 soc id in
power.c.

Change-Id: I00e8e18f6de4ee7b38269e4bf565954db46148c5