The hbd transform configurations were originally written for all possible
2d transforms. Now that there are many more possible 2d transforms
due to EXT_TX and RECT_TX, it is simpler to write the cfg for the
4 1D transform types and compose them to make all new possible transform
types. This will allow for an easier integration of the identity transform
for EXT_TX and rectangular transforms for RECT_TX into the current
hbd transform codepath and facilitate the removal of obsolete transforms.
This has no impact on performance.

BUG=aomedia:524

Change-Id: I1e217bcd217fd637b1df94fae62d9c59a0523c1a