[media] adv7511: drop adv7511_set_IT_content_AVI_InfoFrame

The IT Content bit has nothing to do with CE vs IT timings.
Delete this code. This will also fix a bug where this could
override the 'content type' control, which is actually the
correct place to set/clear the ITC bit.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>