V4L/DVB (13983): [STV6110x] add clk_div member to stv6110x_config structure

Using clk_div member of stv6110x_config structure the tuner's clock
output divider can be configured. It is set in stv6110x_attach.

Signed-off-by: Andreas Regel <andreas.regel@gmx.de>
Signed-off-by: Manu Abraham <manu@linuxtv.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>