For the sake of completeness, include the "undefined" input type enumeration,
even though there is no path that can actually call it.

Thanks to Mauro Carvalho Chehab <mchehab@infradead.org> for pointing this out.
Signed-off-by: Devin Heitmueller <dheitmueller@linuxtv.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>