Alter adjustment of two pass GF/ARF boost with Q.

Delete gfboost_qadjust() and move Q based adjustment
into calc_frame_boost(). Also remove clamping. Making
the adjustment here means that it influences not just the
boost level but also the selection of the GF/ARF interval.

This change gives a small average gain in PSNR but
larger gains in SSIM, especially for harder std-hd set (1.5%)

Change-Id: I3aa81b8feccaeff93d915e19fb9cf5cd64c86327