The following functions use the count parameter to either loop or select
dedicated paths:
vp9_lpf_horizontal_16_c
vp9_lpf_horizontal_16_sse2
vp9_lpf_horizontal_16_avx2
vp9_lpf_horizontal_16_neon
vp9_highbd_lpf_horizontal_16_c
vp9_highbd_lpf_horizontal_16_sse2

Change-Id: I7abfd2cb30baa292b4ebe11c847968481103c037