sctp: define subscribe in sctp_sock as __u16

The member subscribe in sctp_sock is used to indicate to which of
the events it is subscribed, more like a group of flags. So it's
better to be defined as __u16 (2 bytpes), instead of struct
sctp_event_subscribe (13 bytes).

Note that sctp_event_subscribe is an UAPI struct, used on sockopt
calls, and thus it will not be removed. This patch only changes
the internal storage of the flags.

Signed-off-by: Xin Long <lucien.xin@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/sctp/chunk.c

@@ -109,8 +109,8 @@ static void sctp_datamsg_destroy(struct sctp_datamsg *msg)
 				error = asoc->outqueue.error;
 
 			sp = sctp_sk(asoc->base.sk);
-			notify = sctp_ulpevent_type_enabled(SCTP_SEND_FAILED,
-							    &sp->subscribe);
+			notify = sctp_ulpevent_type_enabled(sp->subscribe,
+							    SCTP_SEND_FAILED);
 		}
 
 		/* Generate a SEND FAILED event only if enabled. */