V4L/DVB (5418): Speed is a signed 32-bit integer, not unsigned.

Negative speed values have to be allowed for reverse playback.
Signed-off-by: NHans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: NMauro Carvalho Chehab <mchehab@infradead.org>

include/linux/dvb/video.h

@@ -110,7 +110,7 @@ struct video_command {
 		} stop;
 
 		struct {
-			__u32 speed;
+			__s32 speed;
 			__u32 format;
 		} play;