[media] pvrusb2: Clean up pvr2_hdw_get_detected_std()

Move full implementation of pvr2_hdw_get_detected_std() actually
include pvr2_hdw_get_detected_std().

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