Early terminate interp filt search based on best RD cost

Early terminate interp filt search based on best RD cost

The CL prunes interpolation filter search based on rdcost of
individual planes.

                 Instruction Count        BD-Rate Loss(%)
cpu   Resolution   Reduction(%)    avg.psnr   ovr.psnr    ssim
 0       LOWRES2      1.613         0.0143     0.0208    0.0146
 0       MIDRES2      1.637         0.0214    -0.0316    0.0036
 0        HDRES2      1.369         0.0171     0.0178    0.1222
 0       Average      1.539         0.0176     0.0023    0.0468

STATS_CHANGED

Change-Id: I4be30bd1c7bbbc93c6bbc840565893a97d2598a4