net/smc: introduce sub-functions for smc_clc_send_confirm_accept()

There is a large if-else block in smc_clc_send_confirm_accept() and it
is better to split it into two sub-functions.

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>