Change band calculation back to simpler model based
on the order in which coefficients are coded in scan order
not the absolute coefficient positions.

With the scatter scan experiment enabled the results were
appear broadly neutral on derf (-0.028) but up a little on std-hd +0.134).

Without the scatterscan experiment on the results were up derf as well.

Change-Id: Ie9ef03ce42a6b24b849a4bebe950d4a5dffa6791