vp9: Remove a redundent condition in sub-pixel filter choosing.
vp9: Remove a redundent condition in sub-pixel filter choosing.

Change-Id: I5cbb0f452ec9622437482b3a9496ead1253acfe0

webmproject/libvpx,mbebenita/aom,Topopiccione/libvpx,mbebenita/aom,mwgoldsmith/libvpx,Topopiccione/libvpx,smarter/aom,GrokImageCompression/aom,ShiftMediaProject/libvpx,mbebenita/aom,luctrudeau/aom,Topopiccione/libvpx,ShiftMediaProject/libvpx,ShiftMediaProject/libvpx,mbebenita/aom,mwgoldsmith/libvpx,luctrudeau/aom,webmproject/libvpx,luctrudeau/aom,GrokImageCompression/aom,Topopiccione/libvpx,GrokImageCompression/aom,ShiftMediaProject/libvpx,mwgoldsmith/vpx,smarter/aom,mwgoldsmith/libvpx,mbebenita/aom,mwgoldsmith/libvpx,mwgoldsmith/libvpx,webmproject/libvpx,smarter/aom,mbebenita/aom,ShiftMediaProject/libvpx,smarter/aom,mwgoldsmith/vpx,webmproject/libvpx,smarter/aom,mwgoldsmith/vpx,webmproject/libvpx,mwgoldsmith/vpx,GrokImageCompression/aom,mbebenita/aom,mbebenita/aom,mbebenita/aom,luctrudeau/aom,mwgoldsmith/vpx,Topopiccione/libvpx,Topopiccione/libvpx,mwgoldsmith/libvpx,smarter/aom,webmproject/libvpx,luctrudeau/aom,luctrudeau/aom,mwgoldsmith/vpx,GrokImageCompression/aom,GrokImageCompression/aom