RDMA/hns: Add debugfs support for DCA

driver inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I63KVU



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This patch synchonize DCA code from CI and is based on RFC v2 from the
community including DCA kernel suuport and debugfs support.

Add a group of debugfs files for DCA memory pool statistics.

The debugfs entries for DCA memory statistics include:
hns_roce/<ibdev_name>/dca/qp : show all DCA QPs for each device.
hns_roce/<ibdev_name>/dca/pool : show all DCA mem for each device.
hns_roce/<ibdev_name>/<pid>/qp : show all active DCA QPs for one process.
hns_roce/<ibdev_name>/<pid>/mstats : show DCA mem info for one process.

Signed-off-by: Chengchang Tang <tangchengchang@huawei.com>
Reviewed-by: Yangyang Li <liyangyang20@huawei.com>
Reviewed-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>