perf.profiles: cores online when setting

If cores are not online when setting freqs or governors, the
settings will not work because the files in /sys/... do not
exit when offline.

Change-Id: I6273bcc8f648d7694de86a4c1857d0b6715eb668
Merge pull request #8 from CyanogenMod/cm-11.0

perf.profiles: cores online when setting