New loop filter interface

New loop filter interface

Separate simple filter with reduced no. of parameters.
MB filter level picking based on precalculated table. Level table updated for
each frame. Inside and edge limits precalculated and updated just when
sharpness changes. HEV threshhold is constant.
ARM targets use scalars and others vectors.

Change works only with --target=generic-gnu
All other targets have to be updated!

Change-Id: I6b73aca6b525075b20129a371699b2561bd4d51c