sctp: get list_of_streams of strreset outreq earlier

Now when processing strreset out responses, it gets outreq->list_of_streams
only when result is performed. But if result is not performed, str_p will
be NULL. It will cause panic in sctp_ulpevent_make_stream_reset_event if
nums is not 0.

This patch is to fix it by getting outreq->list_of_streams earlier, and
also to improve some codes for the strreset inreq process.

Signed-off-by: Xin Long <lucien.xin@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>