avdevice/lavfi: Remove unnecessary avio_internal.h inclusion

The stuff declared in said header is actually unusable in libavdevice.
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>

libavdevice/lavfi.c

@@ -39,7 +39,6 @@
 #include "libavutil/pixdesc.h"
 #include "libavfilter/avfilter.h"
 #include "libavfilter/buffersink.h"
-#include "libavformat/avio_internal.h"
 #include "libavformat/internal.h"
 #include "avdevice.h"