sctp: delete unused macro definition of sctp_chunk_is_control

The macro never be used.
And if needed, can use !sctp_chunk_is_data instead of.

Signed-off-by: Shan Wei <shanwei@cn.fujitsu.com>
Signed-off-by: Vlad Yasevich <vladislav.yasevich@hp.com>
Signed-off-by: Wei Yongjun <yjwei@cn.fujitsu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/sctp/constants.h

@@ -150,7 +150,6 @@ SCTP_SUBTYPE_CONSTRUCTOR(OTHER,		sctp_event_other_t,	other)
 SCTP_SUBTYPE_CONSTRUCTOR(PRIMITIVE,	sctp_event_primitive_t,	primitive)
 
 
-#define sctp_chunk_is_control(a) (a->chunk_hdr->type != SCTP_CID_DATA)
 #define sctp_chunk_is_data(a) (a->chunk_hdr->type == SCTP_CID_DATA)
 
 /* Calculate the actual data size in a data chunk */