IB/hns: Fix the bug with modifying the MAC address without removing the driver

When modified the MAC address used hns_roce_mac function, we release and create
reserved qp again, It is not necessary to use spin_lock_bh and spin_unlock_bh in
handle_en_event, Otherwise, it will occur a error. This patch mainly fixes it.

Signed-off-by: Lijun Ou <oulijun@huawei.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>