V4L/DVB (13982): [STV090x] setup master clock in stv090x_init instead of stv090x_setup.

This is needed when clock input is driven from tuner and an output
divider different from 1 is used.

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>