V4L/DVB (13985): [STV090x] reset mclk and dev_ver of internal structure after allocating

When mclk is not 0 then it will never be set to the correct value and
the Demodulator will not work.

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>