staging: vc04_services: Remove function vchiu_queue_is_full()

Remove unused function vchiu_queue_is_full.
Issue found with Coccinelle.

Signed-off-by: Nishka Dasgupta <nishkadg.linux@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>