This patch removes dead code and prevents future implementations
to rely on obsolete transforms. Future optimizations and tests should
be based on latest C-functions (av1/common/av1_inv_txfm1d.c)

Cleanup related last unit-test callers.
BUG=aomedia:442

Change-Id: I24953cc1baf30dd7b720df8a72dd91b356b74cad