[DCCP]: Make `before' relation unambiguous

Problem:

net/dccp/dccp.h

@@ -124,14 +124,11 @@ static inline s64 dccp_delta_seqno(const u64 seqno1, const u64 seqno2)
 /* is seq1 < seq2 ? */
 static inline int before48(const u64 seq1, const u64 seq2)
 {
-	return (s64)((seq1 << 16) - (seq2 << 16)) < 0;
+	return (s64)((seq2 << 16) - (seq1 << 16)) > 0;
 }
 
 /* is seq1 > seq2 ? */
-static inline int after48(const u64 seq1, const u64 seq2)
-{
-	return (s64)((seq2 << 16) - (seq1 << 16)) < 0;
-}
+#define after48(seq1, seq2)	before48(seq2, seq1)
 
 /* is seq2 <= seq1 <= seq3 ? */
 static inline int between48(const u64 seq1, const u64 seq2, const u64 seq3)