media: dvb: dmxdev: move compat_ioctl handling to dmxdev.c

All dmx ioctls are compatible, and they are only implemented
in one file, so we can replace the list of commands in
fs/compat_ioctl.c with a single line in dmxdev.

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