Enables Wiener based loop restoration only for the UV
frames. The selfguided and domaintranform filters do not
work very well for UV components, hence they are disabled.
For each UV frame a single set of wiener parameters are
sent. They are applied tile-wise, but all tiles use the
same parameters.

BDRATE (Global PSNR) results:
-----------------------------
lowres: -1.266% (up from -0.666%, good improvement)
midres: -1.815% (up from -1.792%, tiny improvement)

Tiling on UV components will be explored subsequently.

Change-Id: Ib5be93121c4e88e05edf3c36c46488df3cfcd1e2