Fix THD with max user EQ preset volume again

There was a problem with previous fix in 1b6c677c where
the THD was good for max volume but bad for intermediate
high volume values.

This fix does not limit the band gains but apply a correction
to the effect bundle volume to take into account not only the
maximum band gain but also the average band gains weighted
by the proximity of each band to the max gain band.

Change-Id: Ibedd8da7fce1e163117f29b3da332da0e4fe8889