sctp: remove the useless check in sctp_renege_events

Remove the 'if (chunk)' check in sctp_renege_events for idata process,
as all renege commands are generated in sctp_eat_data and it can't be
NULL.

The same thing we already did for common data in sctp_ulpq_renege.

Fixes: 94014e8d ("sctp: implement renege_events for sctp_stream_interleave")
Signed-off-by: NXin Long <lucien.xin@gmail.com>
Acked-by: NMarcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Acked-by: NNeil Horman <nhorman@tuxdriver.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/sctp/stream_interleave.c

@@ -954,12 +954,8 @@ static void sctp_renege_events(struct sctp_ulpq *ulpq, struct sctp_chunk *chunk,
 	__u32 freed = 0;
 	__u16 needed;
 
-	if (chunk) {
-		needed = ntohs(chunk->chunk_hdr->length);
-		needed -= sizeof(struct sctp_idata_chunk);
-	} else {
-		needed = SCTP_DEFAULT_MAXWINDOW;
-	}
+	needed = ntohs(chunk->chunk_hdr->length) -
+		 sizeof(struct sctp_idata_chunk);
 
 	if (skb_queue_empty(&asoc->base.sk->sk_receive_queue)) {
 		freed = sctp_ulpq_renege_list(ulpq, &ulpq->lobby, needed);