sctp: signal sk_data_ready earlier on data chunks reception

Dave Miller pointed out that fb586f2530 ("sctp: delay calls to
sk_data_ready() as much as possible") may insert latency specially if
the receiving application is running on another CPU and that it would be
better if we signalled as early as possible.

This patch thus basically inverts the logic on fb586f2530 and signals
it as early as possible, similar to what we had before.

Fixes: fb586f2530 ("sctp: delay calls to sk_data_ready() as much as possible")
Reported-by: Dave Miller <davem@davemloft.net>
Signed-off-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/sctp/structs.h

@@ -218,7 +218,7 @@ struct sctp_sock {
 		frag_interleave:1,
 		recvrcvinfo:1,
 		recvnxtinfo:1,
-		pending_data_ready:1;
+		data_ready_signalled:1;
 
 	atomic_t pd_mode;
 	/* Receive to here while partial delivery is in effect. */