Simplify set_rt_speed_feature()

1. Made speed choices to be progressive
2. Adjusted rt speed settings to achieve better speed/quality

Overall, rt-5 gained 2.5% in compression/quality, encoding time of 720p
niklas clip goes from 137,052ms to 121,874ms

Change-Id: Ia6e7e1e15225395a868a2f1059c3db8e266e1600