Renaming vp9_short_fdct4x4 and vp9_short_walsh4x4.

For consistency with idct function names. Renames:
  vp9_short_fdct4x4  -> vp9_fdct4x4
  vp9_short_walsh4x4 -> vp9_fwht4x4

Change-Id: Id15497cc1270acca626447d846f0ce9199770f58
6 files changed