av1/encoder/x86/wedge_utils_sse2: fix int sanitizer warnings

implicit conversion from type 'int' of value 65535 (32-bit, signed)
to type 'short' changed the value to -1 (16-bit, signed)

BUG=aomedia:2357

Change-Id: I7ebd709930347b114be4aef99ff8a5d8d9edca4f
diff --git a/av1/encoder/x86/wedge_utils_sse2.c b/av1/encoder/x86/wedge_utils_sse2.c
index 8dc4bc5..f3f4b8a 100644
--- a/av1/encoder/x86/wedge_utils_sse2.c
+++ b/av1/encoder/x86/wedge_utils_sse2.c
@@ -193,8 +193,8 @@
  */
 void av1_wedge_compute_delta_squares_sse2(int16_t *d, const int16_t *a,
                                           const int16_t *b, int N) {
-  const __m128i v_neg_w =
-      _mm_set_epi16(0xffff, 0, 0xffff, 0, 0xffff, 0, 0xffff, 0);
+  const __m128i v_neg_w = _mm_set_epi16((short)0xffff, 0, (short)0xffff, 0,
+                                        (short)0xffff, 0, (short)0xffff, 0);
 
   assert(N % 64 == 0);