ffmpeg: remove unneeded include "libswscale/swscale.h"

Found-by: ramiro
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

ffmpeg.c

@@ -40,7 +40,6 @@
 #endif
 #include "libavformat/avformat.h"
 #include "libavdevice/avdevice.h"
-#include "libswscale/swscale.h"
 #include "libswresample/swresample.h"
 #include "libavutil/opt.h"
 #include "libavutil/channel_layout.h"