saa716x: initialize si2168_config struct
When new parameters are added for si2168 driver, the parameters have to be explicitly defined for each device if the
si2168_config struct is not initialized to all zeros.

Signed-off-by: Olli Salonen <olli.salonen@iki.fi>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>

Credits: trsqr
saa716x: initialize si2157_config struct
Thanks to whoever came up with this.
Merge pull request #50 from bas-t/latest

saa716x: initialize si2168_config struct