qlcnic: add missing destroy_workqueue() on error path in qlcnic_probe()

Add the missing destroy_workqueue() before return from
qlcnic_probe() in the error handling case.

Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Signed-off-by: David S. Miller <davem@davemloft.net>