sctp: signal sk_data_ready earlier on data chunks reception

sctp: signal sk_data_ready earlier on data chunks reception

Dave Miller pointed out that 49dde45d774a ("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 49dde45d774a and signals
it as early as possible, similar to what we had before.

Fixes: 49dde45d774a ("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>