V4L/DVB (11190): pvrusb2: Broadcast tuner type change to sub-devices

The tuner sub-device isn't going to work very well unless we tell it
the correct tuner type to use...

Signed-off-by: Mike Isely <isely@pobox.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>