net/smc: unify the structs of accept or confirm message for v1 and v2

[ Upstream commit 9505450d ]

The structs of CLC accept and confirm messages for SMCv1 and SMCv2 are
separately defined and often casted to each other in the code, which may
increase the risk of errors caused by future divergence of them. So
unify them into one struct for better maintainability.

Suggested-by: Alexandra Winter <wintera@linux.ibm.com>
Signed-off-by: Wen Gu <guwen@linux.alibaba.com>
Reviewed-by: Alexandra Winter <wintera@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Stable-dep-of: 0541db8e ("net/smc: initialize close_work early to avoid warning")
Signed-off-by: Sasha Levin <sashal@kernel.org>