Currently 4:1 transforms have max 2 split levels:
4:1 -> 1:1 -> 0.5:0.5.

This refactor enables split levels:
4:1 -> 2:1 -> 1:1,

by simply changing the tables in common_data.h.

The actual switch will be made in a subsequent patch.

Change-Id: I33f8d9ca5159ba3e7d02ced449ddf6f804a8f12a