Revert "swscale: Support RGB565 in swscale."

This reverts commit 103ae418.

This cannot be good: either it is invalid or incomplete. More informations
are needed to properly fix the issue seen.

modules/video_filter/swscale.c

@@ -278,9 +278,6 @@ static void FixParameters( int *pi_fmt, bool *pb_has_a, bool *pb_swap_uv, vlc_fo
         *pi_fmt = PIX_FMT_YUV410P;
         *pb_swap_uv = true;
         break;
-    case VLC_CODEC_RGB16:
-        *pi_fmt = PIX_FMT_RGB565;
-        break;
     default:
         break;
     }