RDMA/hns: Add judgment on the execution result of CMDQ that free vf resource

CDMQ may fail to execute, so its return value should not be ignored.

Link: https://lore.kernel.org/r/20220409083254.9696-5-liangwenpeng@huawei.com
Signed-off-by: Wenpeng Liang <liangwenpeng@huawei.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>