IB/hns: Fix bug of using uninit refcount and free

In current version, it uses uninitialized parameters named
refcount and free in hns_roce_cq_event.
This patch initializes these parameter in cq alloc and add
correspond process in cq free.

Signed-off-by: Lijun Ou <oulijun@huawei.com>
Signed-off-by: Dongdong Huang(Donald) <hdd.huang@huawei.com>
Reviewed-by: Wei Hu <xavier.huwei@huawei.com>
Signed-off-by: Salil Mehta <salil.mehta@huawei.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>