we should use free_irq to free the nic irq during the unloading time.
because we use request_irq to apply it when nic up. It will crash if
up net device after reset the port. This patch fixes the issue.
Signed-off-by: qumingguang <qumingguang@huawei.com> Signed-off-by: Lipeng <lipeng321@huawei.com> Signed-off-by: Yunsheng Lin <linyunsheng@huawei.com> Signed-off-by: David S. Miller <davem@davemloft.net>