Revert "sctp: fix call to SCTP_CMD_PROCESS_SACK in sctp_cmd_interpreter()"

This reverts commit c2f5b750 which is
commit f6e80abe.

Michal writes:
	Mainline commit f6e80abe was introduced in v3.7-rc2 as a
	follow-up fix to commit

	  edfee033  sctp: check src addr when processing SACK to update transport state

	(from v3.7-rc1) which changed the interpretation of third
	argument to sctp_cmd_process_sack() and sctp_outq_sack(). But as
	commit edfee033 has never been backported to stable branches,
	backport of commit f6e80abe actually breaks the code rather than
	fixing it.
Reported-by: Michal Kubecek <mkubecek@suse.cz>
Cc: Zijie Pan <zijie.pan@6wind.com>
Cc: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Cc: Vlad Yasevich <vyasevich@gmail.com>
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

net/sctp/sm_sideeffect.c

@@ -1610,9 +1610,8 @@ static int sctp_cmd_interpreter(sctp_event_t event_type,
 					asoc->outqueue.outstanding_bytes;
 			sackh.num_gap_ack_blocks = 0;
 			sackh.num_dup_tsns = 0;
-			chunk->subh.sack_hdr = &sackh;
 			sctp_add_cmd_sf(commands, SCTP_CMD_PROCESS_SACK,
-					SCTP_CHUNK(chunk));
+					SCTP_SACKH(&sackh));
 			break;
 
 		case SCTP_CMD_DISCARD_PACKET: