[media] radio-si470x-usb: Remove software version check

We've an user reporting a device with a software version of 0, which works
fine. Once we lower the version check to accept version 0 it becomes a nop,
so remove it completely.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>