rdma/siw: Remove set but not used variable 's'

Fixes gcc '-Wunused-but-set-variable' warning:

drivers/infiniband/sw/siw/siw_cm.c: In function siw_cm_llp_state_change:
drivers/infiniband/sw/siw/siw_cm.c:1278:17: warning: variable s set but not used [-Wunused-but-set-variable]

Fixes: 6c52fdc2 ("rdma/siw: connection management")
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Reviewed-by: Bernard Metzler <bmt@zurich.ibm.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>