[media] tm6000: Use correct input in radio mode

In radio mode, the correct input is rinput. The pseudo index 5 is used
but cannot be used to index the vinput array because that only has 3
elements.

Signed-off-by: Thierry Reding <thierry.reding@avionic-design.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>