Increase the CPU load threshold and monitor the longer period

For webRTC use-case, allow 8x10 to run up to 95% of CPU utilization
before letting load manager lowering the FPS to 20 or lower.
In addition, monitors the CPU load for longer period to avoid
unnecessary FPS/resolution changing due to a short CPU usage hike.

Change-Id: I82d05700ef0e5f7c0b953f7dce3fc86d852ac2d5