6lowpan: move mac802154 header

In case of link-layer specific handling for 802.15.4 we need to cast to
802.15.4 sepcific structures. Simple add this header when include the
6lowpan header.
Signed-off-by: Alexander Aring <aar@pengutronix.de>
Reviewed-by: Stefan Schmidt<stefan@osg.samsung.com>
Acked-by: Jukka Rissanen <jukka.rissanen@linux.intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

include/net/6lowpan.h

@@ -58,6 +58,9 @@
 #include <net/ipv6.h>
 #include <net/net_namespace.h>
 
+/* special link-layer handling */
+#include <net/mac802154.h>
+
 #define EUI64_ADDR_LEN		8
 
 #define LOWPAN_NHC_MAX_ID_LEN	1

net/6lowpan/iphc.c

@@ -53,9 +53,6 @@
 #include <net/6lowpan.h>
 #include <net/ipv6.h>
 
-/* special link-layer handling */
-#include <net/mac802154.h>
-
 #include "6lowpan_i.h"
 #include "nhc.h"