V4L/DVB (7911): Remove v4l2_video_std_fps prototype declaration

The v4l2_video_std_fps function has been removed by Adrian Bunk in 2004
but then its prototype re-appeared in include/media/v4l2-dev.h. Remove it.

Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>