Update xc4000 tuner definition, number 81 is already in use by
TUNER_PARTSNIC_PTI_5NF05.

Cc: stable@kernel.org
Signed-off-by: NMiroslav Slugen <thunder.mmm@gmail.com>
Signed-off-by: NMauro Carvalho Chehab <mchehab@redhat.com>