ip: introduce ip_is_fragment helper inline function

There are enough instances of this:

    iph->frag_off & htons(IP_MF | IP_OFFSET)

that a helper function is probably warranted.

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/sched/cls_flow.c b/net/sched/cls_flow.c
index 8ec0139..34533a5 100644
--- a/net/sched/cls_flow.c
+++ b/net/sched/cls_flow.c
@@ -121,7 +121,7 @@
 		if (!pskb_network_may_pull(skb, sizeof(*iph)))
 			break;
 		iph = ip_hdr(skb);
-		if (iph->frag_off & htons(IP_MF | IP_OFFSET))
+		if (ip_is_fragment(iph))
 			break;
 		poff = proto_ports_offset(iph->protocol);
 		if (poff >= 0 &&
@@ -163,7 +163,7 @@
 		if (!pskb_network_may_pull(skb, sizeof(*iph)))
 			break;
 		iph = ip_hdr(skb);
-		if (iph->frag_off & htons(IP_MF | IP_OFFSET))
+		if (ip_is_fragment(iph))
 			break;
 		poff = proto_ports_offset(iph->protocol);
 		if (poff >= 0 &&