xfrm: Remove unused defines

XFRM_REPLAY_SEQ, XFRM_REPLAY_OSEQ and XFRM_REPLAY_SEQ_MASK
were introduced years ago but actually never used.
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>

include/net/xfrm.h

@@ -557,10 +557,6 @@ struct xfrm_migrate {
 };
 
 #define XFRM_KM_TIMEOUT                30
-/* which seqno */
-#define XFRM_REPLAY_SEQ		1
-#define XFRM_REPLAY_OSEQ	2
-#define XFRM_REPLAY_SEQ_MASK	3
 /* what happened */
 #define XFRM_REPLAY_UPDATE	XFRM_AE_CR
 #define XFRM_REPLAY_TIMEOUT	XFRM_AE_CE