ipv6: add ip6_flowlabel helper

And use it if possible.

Signed-off-by: Florent Fourcot <florent.fourcot@enst-bretagne.fr>
Reviewed-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/net/ipv6.h b/include/net/ipv6.h
index bce802e..d0bfe3e 100644
--- a/include/net/ipv6.h
+++ b/include/net/ipv6.h
@@ -679,6 +679,11 @@
 	return *(__be32 *)hdr & IPV6_FLOWINFO_MASK;
 }
 
+static inline __be32 ip6_flowlabel(const struct ipv6hdr *hdr)
+{
+	return *(__be32 *)hdr & IPV6_FLOWLABEL_MASK;
+}
+
 /*
  *	Prototypes exported by ipv6
  */