sctp: fix sparse warning for sctp_init_cause_fixed

Fix the following sparse warning:
	* symbol 'sctp_init_cause_fixed' was not declared. Should it be
	  static?
Signed-off-by: NIoan Orghici <ioanorghici@gmail.com>
Acked-by: NVlad Yasevich <vyasevich@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/sctp/sm_make_chunk.c

@@ -132,7 +132,7 @@ void  sctp_init_cause(struct sctp_chunk *chunk, __be16 cause_code,
  * abort chunk.  Differs from sctp_init_cause in that it won't oops
  * if there isn't enough space in the op error chunk
  */
-int sctp_init_cause_fixed(struct sctp_chunk *chunk, __be16 cause_code,
+static int sctp_init_cause_fixed(struct sctp_chunk *chunk, __be16 cause_code,
 		      size_t paylen)
 {
 	sctp_errhdr_t err;