Fix order of arguments in fib[46]_lookup calls in SCTP.

r360292 introduced the wrong order, resulting in returned
nhops not being referenced, despite the fact that references
were requested. That lead to random GPF after using SCTP sockets.

Special defined macro like IPV[46]_SCOPE_GLOBAL will be introduced
soon to reduce the chance of putting arguments in wrong order.

Reported-by: syzbot+5c813c01096363174684@syzkaller.appspotmail.com