[media] ivtv-i2c: Don't use IR legacy mode for Zilog IR

The Zilog IR entries are already handled by IR new code. So,
remove its usage from the legacy IR support.

Acked-by: Andy Walls <awalls@md.metrocast.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>