Revert "Clean up aom_highbd_upsampled_pred_sse2"

This reverts commit 286ed991dd293b5e8e38e3a1d0fbf3bc10f1c9ff.

Reason for revert:
This patch caused a valgrind issue. Reverted the patch for now so that we have time to resolve it.

BUG=aomedia:2216

Change-Id: Ie7a471c2a004e52cf0da8e38d9a2e78826185216
diff --git a/aom_dsp/x86/highbd_variance_sse2.c b/aom_dsp/x86/highbd_variance_sse2.c
index 226576b..b17573e 100644
--- a/aom_dsp/x86/highbd_variance_sse2.c
+++ b/aom_dsp/x86/highbd_variance_sse2.c
@@ -734,6 +734,16 @@
     const int intermediate_height =
         (((height - 1) * 8 + subpel_y_q3) >> 3) + filter_taps;
     assert(intermediate_height <= (MAX_SB_SIZE * 2 + 16) + 16);
+    // TODO(Sachin): Remove the memset below when we have
+    // 4 tap simd for avx2.
+    if (subpel_search <= USE_4_TAPS) {
+      memset(temp_start_vert - 3 * MAX_SB_SIZE, 0, width * sizeof(uint16_t));
+      memset(temp_start_vert - 2 * MAX_SB_SIZE, 0, width * sizeof(uint16_t));
+      memset(temp_start_vert + (height + 2) * MAX_SB_SIZE, 0,
+             width * sizeof(uint16_t));
+      memset(temp_start_vert + (height + 3) * MAX_SB_SIZE, 0,
+             width * sizeof(uint16_t));
+    }
     aom_highbd_convolve8_horiz(
         ref_start, ref_stride, CONVERT_TO_BYTEPTR(temp_start_horiz),
         MAX_SB_SIZE, kernel_x, 16, NULL, -1, width, intermediate_height, bd);