cxgb4: Fix incorrect 'c' suffix to %pI4, use %pISc instead

Issue caught by 0-day kernel test infrastructure. Code changed to use sockaddr
members so that %pISc can be used instead.

Fixes: b5a02f50 ('cxgb4 : Update ipv6 address handling api')

Signed-off-by: Anish Bhatt <anish@chelsio.com>
Signed-off-by: David S. Miller <davem@davemloft.net>