RDMA/hns: Remove unused function to_hns_roce_state()

This function is only used in HIP06, which has been removed. So remove it.

Link: https://lore.kernel.org/r/20220409083254.9696-3-liangwenpeng@huawei.com


Signed-off-by: Yixing Liu <liuyixing1@huawei.com>
Signed-off-by: Wenpeng Liang <liangwenpeng@huawei.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>