vp9: Update to noise estimation for denoising.
vp9: Update to noise estimation for denoising.

Change initial state of noise level, and only update
denoiser with noise level when estimate is done.

Change-Id: If44090d29949d3e4927e855d88241634cdb395dc

thdav/aom,mwgoldsmith/libvpx,openpeer/libvpx_new,webmproject/libvpx,mwgoldsmith/libvpx,luctrudeau/aom,mbebenita/aom,shacklettbp/aom,mwgoldsmith/vpx,ittiamvpx/libvpx-1,ShiftMediaProject/libvpx,smarter/aom,luctrudeau/aom,openpeer/libvpx_new,smarter/aom,ShiftMediaProject/libvpx,shacklettbp/aom,GrokImageCompression/aom,smarter/aom,mbebenita/aom,mbebenita/aom,openpeer/libvpx_new,luctrudeau/aom,thdav/aom,GrokImageCompression/aom,shacklettbp/aom,ShiftMediaProject/libvpx,jmvalin/aom,ShiftMediaProject/libvpx,jmvalin/aom,mwgoldsmith/libvpx,webmproject/libvpx,openpeer/libvpx_new,webmproject/libvpx,mwgoldsmith/vpx,openpeer/libvpx_new,ittiamvpx/libvpx-1,thdav/aom,thdav/aom,GrokImageCompression/aom,webmproject/libvpx,mwgoldsmith/libvpx,mbebenita/aom,mbebenita/aom,ittiamvpx/libvpx-1,Topopiccione/libvpx,openpeer/libvpx_new,mbebenita/aom,ittiamvpx/libvpx-1,jmvalin/aom,jmvalin/aom,thdav/aom,webmproject/libvpx,shacklettbp/aom,Topopiccione/libvpx,GrokImageCompression/aom,smarter/aom,GrokImageCompression/aom,thdav/aom,luctrudeau/aom,smarter/aom,mwgoldsmith/vpx,mwgoldsmith/libvpx,luctrudeau/aom,jmvalin/aom,Topopiccione/libvpx,mbebenita/aom,ittiamvpx/libvpx-1,mwgoldsmith/vpx,shacklettbp/aom,Topopiccione/libvpx,mwgoldsmith/vpx,mwgoldsmith/libvpx,mbebenita/aom,ShiftMediaProject/libvpx,ittiamvpx/libvpx-1,mbebenita/aom,luctrudeau/aom,mwgoldsmith/vpx,smarter/aom,shacklettbp/aom,Topopiccione/libvpx,Topopiccione/libvpx,GrokImageCompression/aom,webmproject/libvpx,jmvalin/aom