V4L/DVB (3403): Add probe check for the tda9840.

- Add probe check for the tda9840 to prevent misdetection of a Micronas
  dpl3518a as a tda9840.

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