dccp: clean up unused DCCP_STATE_MASK definition

Remove unused DCCP_STATE_MASK macro.
Signed-off-by: NShan Wei <shanwei@cn.fujitsu.com>
Acked-by: NGerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

include/linux/dccp.h

@@ -279,8 +279,6 @@ enum dccp_state {
 	DCCP_MAX_STATES
 };
 
-#define DCCP_STATE_MASK 0x1f
-
 enum {
 	DCCPF_OPEN	      = TCPF_ESTABLISHED,
 	DCCPF_REQUESTING      = TCPF_SYN_SENT,