[media] rc5-decoder: BZ#85721: Fix RC5-SZ decoding

Changeset e87b540b

 broke RC5-SZ decoding, as it forgot to add
the extra bit check for the enabled protocols at the beginning of
the logic.

Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
Acked-by: David Härdeman <david@hardeman.nu>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>