[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/ipv4/inet_timewait_sock.c b/net/ipv4/inet_timewait_sock.c
index 2586df0..4e189e2 100644
--- a/net/ipv4/inet_timewait_sock.c
+++ b/net/ipv4/inet_timewait_sock.c
@@ -8,7 +8,7 @@
  *		From code orinally in TCP
  */
 
-
+#include <linux/kernel.h>
 #include <net/inet_hashtables.h>
 #include <net/inet_timewait_sock.h>
 #include <net/ip.h>
@@ -292,7 +292,7 @@
 		if (timeo >= timewait_len) {
 			slot = INET_TWDR_TWKILL_SLOTS - 1;
 		} else {
-			slot = (timeo + twdr->period - 1) / twdr->period;
+			slot = DIV_ROUND_UP(timeo, twdr->period);
 			if (slot >= INET_TWDR_TWKILL_SLOTS)
 				slot = INET_TWDR_TWKILL_SLOTS - 1;
 		}