[media] typhoon: convert to unlocked_ioctl

Convert the typhoon driver from ioctl to unlocked_ioctl.

When doing this I noticed a bug where curfreq was not initialized correctly
to mutefreq (it wasn't multiplied by 16).

The initialization is now also done before the device node is created.

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