VP9: Only zero counts when !frame_parallel_decoding_mode
VP9: Only zero counts when !frame_parallel_decoding_mode

The counts are never used when frame_parallel_decoding_mode
is set.

Change-Id: Ic7a566a048297f7373c9ffbb48929ea09eff674f

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