media: cx18: fix kernel oops with tda8290 tuner

commit 6a03dc92 upstream.

This was caused by an uninitialized setup.config field.

Based on a suggestion from Devin Heitmueller.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Thanks-to: Devin Heitmueller <dheitmueller@kernellabs.com>
Reported-by: Scott Robinson <scott.robinson55@gmail.com>
Tested-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>