habanalabs: fix incorrect check on failed workqueue create

The null check on a failed workqueue create is currently null checking
hdev->cq_wq rather than the pointer hdev->cq_wq[i] and so the test
will never be true on a failed workqueue create. Fix this by checking
hdev->cq_wq[i].

Addresses-Coverity: ("Dereference before null check")
Fixes: 5574cb21 ("habanalabs: Assign each CQ with its own work queue")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Reviewed-by: Oded Gabbay <oded.gabbay@gmail.com>
Signed-off-by: Oded Gabbay <oded.gabbay@gmail.com>