[media] saa7115: add back the dropped 'found' message

The saa7115 driver used to show a 'chip found' message during probe. This
was accidentally dropped during recent commits. Add it back as it is quite
useful.

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