dccp: use roundup instead of opencoding

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/dccp/output.c b/net/dccp/output.c
index fea30cd..22a618a 100644
--- a/net/dccp/output.c
+++ b/net/dccp/output.c
@@ -175,7 +175,7 @@
 	 * make it a multiple of 4
 	 */
 
-	cur_mps -= ((5 + 6 + 10 + 6 + 6 + 6 + 3) / 4) * 4;
+	cur_mps -= roundup(5 + 6 + 10 + 6 + 6 + 6, 4);
 
 	/* And store cached results */
 	icsk->icsk_pmtu_cookie = pmtu;