net: replace __constant_{endian} uses in net headers

Base versions handle constant folding now.  For headers exposed to
userspace, we must only expose the __ prefixed versions.

Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/net/ipv6.h b/include/net/ipv6.h
index 6d5b58a..c1f16fc 100644
--- a/include/net/ipv6.h
+++ b/include/net/ipv6.h
@@ -196,8 +196,8 @@
 	struct net		*fl_net;
 };
 
-#define IPV6_FLOWINFO_MASK	__constant_htonl(0x0FFFFFFF)
-#define IPV6_FLOWLABEL_MASK	__constant_htonl(0x000FFFFF)
+#define IPV6_FLOWINFO_MASK	cpu_to_be32(0x0FFFFFFF)
+#define IPV6_FLOWLABEL_MASK	cpu_to_be32(0x000FFFFF)
 
 struct ipv6_fl_socklist
 {