Perf: Add cpu boost for overscroller fling.

Use perflock api's to add cpu boost for
overscroller fling. 2 Cores are made online
with minumum 1.1GHz nominal cpu freq for the
duration of the fling.
Cpu boost will be controlled by
config_enableCpuBoostForOverScrollerFling.
Default value of config is false and to turn
on use device specific overlay files.

Change-Id: If0a545e126d157d7e2fdaecc1108d41469172cd6

Conflicts:
	core/res/res/values/config.xml
	core/res/res/values/symbols.xml