[media] lirc_igorplugusb: assorted fixups

Tighten up error checking, rename some functions to less generic names,
remove unnecessary cruft, add missing debug modparam wiring, and fix up
some printk output.

Signed-off-by: Jarod Wilson <jarod@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>