6lowpan: fix udp compress ordering

In case ((ntohs(uh->source) & LOWPAN_NHC_UDP_8BIT_MASK) the order of
uncompression is wrong. It's always first source port then destination
port as second.

See:
http://tools.ietf.org/html/rfc6282#section-4.3.3

"Fields carried in-line (in part or in whole) appear in the same order
as they do in the UDP header format"
Signed-off-by: Alexander Aring <alex.aring@gmail.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

net/ieee802154/6lowpan_iphc.c

@@ -567,9 +567,9 @@ static void compress_udp_header(u8 **hc06_ptr, struct sk_buff *skb)
 		pr_debug("UDP header: remove 8 bits of source\n");
 		tmp = LOWPAN_NHC_UDP_CS_P_10;
 		lowpan_push_hc_data(hc06_ptr, &tmp, sizeof(tmp));
-		lowpan_push_hc_data(hc06_ptr, &uh->dest, sizeof(uh->dest));
 		tmp = (u8)(uh->source - LOWPAN_NHC_UDP_8BIT_PORT);
 		lowpan_push_hc_data(hc06_ptr, &tmp, sizeof(tmp));
+		lowpan_push_hc_data(hc06_ptr, &uh->dest, sizeof(uh->dest));
 	} else {
 		pr_debug("UDP header: can't compress\n");
 		tmp = LOWPAN_NHC_UDP_CS_P_00;