fixed uyvy_to_i420

fix test codec_conversion_test_testcard_uyvy_to_i420 fail caused by the
merge of testcard_common toI420 to to_lavc uyvy_to_yuv420p

Last line was incorrectly checked in case of odd number of lines.

src/pixfmt_conv.c

@@ -3324,7 +3324,7 @@ uyvy_to_i420(unsigned char *__restrict *__restrict out_data,
                 unsigned char *v  = out_data[2] + (i * out_linesize[2]);
 
                 // handle height % 2 == 1
-                if (i + 1 == (size_t) height) {
+                if (2 * i + 1 == (size_t) height) {
                         y2  = y1;
                         in2 = in1;
                 }