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/ipx.h b/include/net/ipx.h
index 4cc0b4e..a14121d 100644
--- a/include/net/ipx.h
+++ b/include/net/ipx.h
@@ -27,7 +27,7 @@
 
 struct ipxhdr {
 	__be16			ipx_checksum __attribute__ ((packed));
-#define IPX_NO_CHECKSUM	__constant_htons(0xFFFF)
+#define IPX_NO_CHECKSUM	cpu_to_be16(0xFFFF)
 	__be16			ipx_pktsize __attribute__ ((packed));
 	__u8			ipx_tctrl;
 	__u8			ipx_type;