Fix memset call for selfguided sse4 code

BUG=aomedia:2152

Change-Id: I8ad52066d1cdccf4f422d246f8e57c5dfd144269

av1/common/x86/selfguided_sse4.c

diff --git a/av1/common/x86/selfguided_sse4.c b/av1/common/x86/selfguided_sse4.c
index cca263b..ea3f6d9 100644
--- a/av1/common/x86/selfguided_sse4.c
+++ b/av1/common/x86/selfguided_sse4.c
@@ -507,7 +507,7 @@
   int32_t *buf = (int32_t *)aom_memalign(
       16, 4 * sizeof(*buf) * RESTORATION_PROC_UNIT_PELS);
   if (!buf) return -1;
-  memset(buf, 0, 4 * RESTORATION_PROC_UNIT_PELS);
+  memset(buf, 0, 4 * sizeof(*buf) * RESTORATION_PROC_UNIT_PELS);
 
   const int width_ext = width + 2 * SGRPROJ_BORDER_HORZ;
   const int height_ext = height + 2 * SGRPROJ_BORDER_VERT;