Rename current wait_tx_queue_empty to wait_tx_queues_empty since
it waits for multiple queues (up to 32).
Next patch will add a wait for single TX queue which is needed for
gen2 to be scalable for 512.
Signed-off-by: NSara Sharon <sara.sharon@intel.com>
Signed-off-by: NLuca Coelho <luciano.coelho@intel.com>