V4L/DVB (8113): ivtv/cx18: remove s/g_ctrl, now all controls are handled through s/g_ext_ctrl

videodev converts old-style controls to an extended control so the ivtv and
cx18 drivers no longer have to handle both.

Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>