media: dvb: move compat handlers into drivers

The VIDEO_STILLPICTURE is only implemented by one driver, while
VIDEO_GET_EVENT has two users in tree. In both cases, it is fairly
easy to handle the compat ioctls in the native handler rather
than relying on translation in fs/compat_ioctls.

In effect, this means that now the drivers implement both structure
layouts in both native and compat mode, but I don't see anything
wrong with that.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>