ieee802154: add netns support

This patch adds netns support for 802.15.4 subsystem. Most parts are
copy&pasted from wireless subsystem, it has the identically userspace
API.

Cc: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Reviewed-by: Stefan Schmidt <stefan@osg.samsung.com>
Signed-off-by: Alexander Aring <aar@pengutronix.de>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
diff --git a/net/ieee802154/core.h b/net/ieee802154/core.h
index 231fade..81141f5 100644
--- a/net/ieee802154/core.h
+++ b/net/ieee802154/core.h
@@ -38,6 +38,8 @@
 extern struct list_head cfg802154_rdev_list;
 extern int cfg802154_rdev_list_generation;
 
+int cfg802154_switch_netns(struct cfg802154_registered_device *rdev,
+			   struct net *net);
 /* free object */
 void cfg802154_dev_free(struct cfg802154_registered_device *rdev);
 struct cfg802154_registered_device *