Fix integer sanitizer warnings: warp_plane_sse4.c

implicit conversion from type 'int' of value -682160376
(32-bit, signed) to type 'short' changed the value to
3848 (16-bit, signed)

BUG=aomedia:2478

Change-Id: Ic9afd9093aebbc45be0ddf4fec7ee6ffd9bf0c3f

av1/common/x86/warp_plane_sse4.c

diff --git a/av1/common/x86/warp_plane_sse4.c b/av1/common/x86/warp_plane_sse4.c
index 6112368..10ddf92 100644
--- a/av1/common/x86/warp_plane_sse4.c
+++ b/av1/common/x86/warp_plane_sse4.c
@@ -462,8 +462,8 @@
 
   const int w0 = conv_params->fwd_offset;
   const int w1 = conv_params->bck_offset;
-  const __m128i wt0 = _mm_set1_epi16(w0);
-  const __m128i wt1 = _mm_set1_epi16(w1);
+  const __m128i wt0 = _mm_set1_epi16((int16_t)w0);
+  const __m128i wt1 = _mm_set1_epi16((int16_t)w1);
   *wt = _mm_unpacklo_epi16(wt0, wt1);
 }