libpower: tuning and cleanups

 * Tune the governor for better power usage and interactivity
 * Reset tuning parameters if governor changes
 * Cleanup

Change-Id: I56f5dcc7f15e5dfbcc38338d515fd41d04662ab1
p350:libpower: Add support for smartass v2 and v3 gov

Change-Id: Ia171857ae86e115f9b42c50304fca207aa9266c2
p350: Make smartassV2 as default governor

Change-Id: I1a06f44f6feccf234bde733e0e0dfa4b83819c90