vp9: Wrap threshold tuning for HD only when denoiser is enabled.
vp9: Wrap threshold tuning for HD only when denoiser is enabled.

Fixes a speed regression.

Change-Id: I23d942e4af17fa81fe4a366c7369b3ad537e59b0

webmproject/libvpx,webmproject/libvpx,webmproject/libvpx,ShiftMediaProject/libvpx,ShiftMediaProject/libvpx,webmproject/libvpx,ShiftMediaProject/libvpx,webmproject/libvpx,webmproject/libvpx,ShiftMediaProject/libvpx,ShiftMediaProject/libvpx