[media] em28xx: tuner setup is broken after algo_data change

Commit aab3125c

 broke em28xx. I traced
this eventually to the change in what algo_data points to. This pointer
is also passed to em28xx_tuner_callback() through several hidden tuner
layers (yuck!) and that callback was not updated.

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