RDMA/srpt: Introduce a reference count in struct srpt_device

stable inclusion
from stable-v5.10.137
commit d14a44cf2919920c61496ff252240fbfc5551faf
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I60PLB

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=d14a44cf2919920c61496ff252240fbfc5551faf

--------------------------------

[ Upstream commit aa7dfbb4 ]

This will be used to keep struct srpt_device around as long as either the
RDMA port exists or a LIO target port is associated with the struct
srpt_device.

Link: https://lore.kernel.org/r/20220727193415.1583860-3-bvanassche@acm.org


Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>
Reviewed-by: Wei Li <liwei391@huawei.com>