src/video_output/display.c: use video_format_IsSimilar() iso of memcmp.

Using memcmp results in false positives (src format and dst format is
exactly the same, but still the logic resulted in loading swscale).

src/video_output/display.c

@@ -394,7 +394,7 @@ static void VoutDisplayCreateRender(vout_display_t *vd)
         (v_src.i_chroma == VLC_CODEC_J444 && v_dst.i_chroma == VLC_CODEC_I444))
         v_dst_cmp.i_chroma = v_src.i_chroma;
 
-    const bool convert = memcmp(&v_src, &v_dst_cmp, sizeof(v_src)) != 0;
+    const bool convert = !video_format_IsSimilar(&v_src, &v_dst_cmp);
     if (!convert)
         return;