[NET]: DIV_ROUND_UP cleanup (part two)

Hopefully captured all single statement cases under net/. I'm
not too sure if there is some policy about #includes that are
"guaranteed" (ie., in the current tree) to be available through
some other #included header, so I just added linux/kernel.h to
each changed file that didn't #include it previously.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/dccp/ackvec.c b/net/dccp/ackvec.c
index 3f8984b..83378f3 100644
--- a/net/dccp/ackvec.c
+++ b/net/dccp/ackvec.c
@@ -69,9 +69,8 @@
 	struct dccp_sock *dp = dccp_sk(sk);
 	struct dccp_ackvec *av = dp->dccps_hc_rx_ackvec;
 	/* Figure out how many options do we need to represent the ackvec */
-	const u16 nr_opts = (av->dccpav_vec_len +
-			     DCCP_MAX_ACKVEC_OPT_LEN - 1) /
-			    DCCP_MAX_ACKVEC_OPT_LEN;
+	const u16 nr_opts = DIV_ROUND_UP(av->dccpav_vec_len,
+					 DCCP_MAX_ACKVEC_OPT_LEN);
 	u16 len = av->dccpav_vec_len + 2 * nr_opts, i;
 	u32 elapsed_time;
 	const unsigned char *tail, *from;