V4L/DVB: saa7146/tuner: remove mxb hack

Remove a hack in the tuner code for the mxb board. This hack is no longer
needed since the tuner is now probed on its correct address as specified
by the mxb driver.

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