sctp: drop unnecessary __packed from some stream reconf structures

commit 85c727b5 ("sctp: drop __packed from almost all SCTP structures")
has removed __packed from almost all SCTP structures. But there still are
three structures where it should be dropped.

This patch is to remove it from some stream reconf structures.

Signed-off-by: Xin Long <lucien.xin@gmail.com>
Acked-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>