SSE2 : use _mm_cvtpd_epi32 when converting from CV_64F to CV_32S (opencv#10987)

* SSE2 : use _mm_cvtpd_epi32 when converting from CV_64F to CV_32S

* No need to define a new universal intrinsic

Author: nglee

modules/core/src/convert.cpp

@@ -770,10 +770,10 @@ struct Cvt_SIMD<double, int>
             int cWidth = v_float64x2::nlanes;
             for (; x <= width - cWidth * 2; x += cWidth * 2)
             {
-                v_float32x4 v_src0 = v_cvt_f32(v_load(src + x));
-                v_float32x4 v_src1 = v_cvt_f32(v_load(src + x + cWidth));
+                v_int32x4 v_src0 = v_round(v_load(src + x));
+                v_int32x4 v_src1 = v_round(v_load(src + x + cWidth));
 
-                v_store(dst + x, v_round(v_combine_low(v_src0, v_src1)));
+                v_store(dst + x, v_combine_low(v_src0, v_src1));
             }
         }
         return x;