RDMA/core: Use refcount_t instead of atomic_t on refcount of iwcm_id_private

[ Upstream commit 60dff56d77292062789232f68354f567e1ccf1d2 ]

The refcount_t API will WARN on underflow and overflow of a reference
counter, and avoid use-after-free risks.

Link: https://lore.kernel.org/r/1622194663-2383-2-git-send-email-liweihang@huawei.com


Signed-off-by: Weihang Li <liweihang@huawei.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Stable-dep-of: 6883b680e703 ("RDMA/iwcm: Fix use-after-free of work objects after cm_id destruction")
Signed-off-by: Sasha Levin <sashal@kernel.org>