[media] v4l2-ioctl.c: prefill tuner type for g_frequency and g/s_tuner

The subdevs are supposed to receive a valid tuner type for the g_frequency
and g/s_tuner subdev ops. Some drivers do this, others don't. So prefill
this in v4l2-ioctl.c based on whether the device node from which this is
called is a radio node or not.

The spec does not require applications to fill in the type, and if they
leave it at 0 then the 'check_mode' call in tuner-core.c will return
an error and the ioctl does nothing.

Cc: stable@kernel.org
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>