Switch to use new skin model.

And fix condition for denoising skin block.
Previous condition did not denoise skin blocks if the selected
mode was non-zero motion in current frame. Modify condition to
also force no denoising if that mode was not selected as zero motion
now and for at least "x" past frames in a row (x = 2).

Change-Id: I00753e3fe45b9a308a7ef43c58f11868e3bfc6b0