This reverts commit 452dc215.

This change has introduced a significant quality regression on content
with forced key frames. (e.g. the YT and yt-hd set). It is most
noticeable in static content where the kf bits dominate. Here, despite
key frames being apparently coded at the same Q, there is a drop in all
metrics of ~20% (e.g clXR and BFa0).

Change-Id: Iba14cc61778c0846fa0a59c33c55a9fc49512cb4