This adds the proper cfgs to av1_{inv/fwd}_txfm1d_cfg for
the identity transform so all hbd transforms can use
the same codepath. This has no impact on performance
since the new identity transforms that correspond with
the cfgs are not yet being called. Once this is checked in,
we should be able to delete all deprecated transform functions
and have a single code flow for all hbd transforms.

BUG=aomedia:524

Change-Id: I3d1bfbc8bc29b367e8ddf7dcd27525af0bd31067