Earlier, the superres scale was in the form of:
N/16, where N ranged from 8 to 16.

We change this to the form:
8/D, where D ranges from 8 to 16.

This helps on the decoder side, by making it possible to work on 8x8
blocks at a time.

Change-Id: I6c72d4b3e8d1c830e61d4bb8d7f6337a100c3064