sctp: fix the missing put_user when dumping transport thresholds

This issue causes SCTP_PEER_ADDR_THLDS sockopt not to be able to dump
a transport thresholds info.

Fix it by adding 'goto' put_user in sctp_getsockopt_paddr_thresholds.

Fixes: 8add543e

 ("sctp: add SCTP_FUTURE_ASSOC for SCTP_PEER_ADDR_THLDS sockopt")
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Acked-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>