DCA(Dynamic context attachment) support many RC QPs to share the WQE
buffer in a memory pool, this help reducing the memory consumption
when there are many QPs are inactive.
Signed-off-by: Chengchang Tang <tangchengchang@huawei.com>
(cherry picked from commit b88a370b79cd9b93f9a587c1e4e0d9c89d0b1d1e)
