Allow the encode loop to select from a wider range of Q values
when encoding normal (non arf or kf) frames.

This change is targeted at improving psycho-visual quality in some
easy sections that are currently not getting enough bits.
This is likely to be a little worse from a metrics perspective  and may also
have a small impact on encode speed in cases where extra recode
iterations are triggered.

Change-Id: I667eebf33c753bcbcf8b93596467369e5708b889