cameraHal: color conv optimization; use cpu governor boost

- speed-up color conversion for preview
- adjust frame drop thresholds and throttled preview fps
- set boost of cpufreq interactive governor when recording video
- reduce number of preview window buffers to required minimum

Change-Id: I4440054a7d27d094c4df28b3a2fb0cf7e930b3c3

Conflicts:

	camera/cameraHal.cpp