AVX2: Remove a couple dead stores

BUG=aomedia:3338

Change-Id: Ie457043f738ab490722bc5960121059c357b8fcd

third_party/SVT-AV1/convolve_avx2.h

diff --git a/third_party/SVT-AV1/convolve_avx2.h b/third_party/SVT-AV1/convolve_avx2.h
index 31d9790..452a713 100644
--- a/third_party/SVT-AV1/convolve_avx2.h
+++ b/third_party/SVT-AV1/convolve_avx2.h
@@ -2195,11 +2195,9 @@
             s_32[1] = _mm_cvtsi32_si128(*(int32_t *)(src_ptr + src_stride));
             const __m128i d0 = _mm_avg_epu8(s_32[0], s_32[1]);
             xx_storel_32(dst, d0);
-            *(uint32_t *)dst = _mm_cvtsi128_si32(d0);
             s_32[0] = _mm_cvtsi32_si128(*(int32_t *)(src_ptr + 2 * src_stride));
             const __m128i d1 = _mm_avg_epu8(s_32[1], s_32[0]);
             xx_storel_32(dst + dst_stride, d1);
-            *(uint32_t *)(dst + dst_stride) = _mm_cvtsi128_si32(d1);
             src_ptr += 2 * src_stride;
             dst += 2 * dst_stride;
             y -= 2;