VP9: remove plane_type checks in loopfilter functions
VP9: remove plane_type checks in loopfilter functions

vp9_filter_block_plane_ss11() and vp9_filter_block_plane_non420()
are only called for the uv planes.

Change-Id: Iacd3b3242c8ce581edd37c8f06d95efc8a0f88a3

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