net/smc: Clean up local struct sock variables

There remains some variables to replace with local struct sock. So clean
them up all.

Fixes: 3163c5071f25 ("net/smc: use local struct sock variables consistently")
Signed-off-by: Tony Lu <tonylu@linux.alibaba.com>
Reviewed-by: Wen Gu <guwen@linux.alibaba.com>
Signed-off-by: David S. Miller <davem@davemloft.net>