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/include/net/cfg802154.h b/include/net/cfg802154.h
index 171cd76..795ca40 100644
--- a/include/net/cfg802154.h
+++ b/include/net/cfg802154.h
@@ -219,9 +219,22 @@
 
 	struct device dev;
 
+	/* the network namespace this phy lives in currently */
+	possible_net_t _net;
+
 	char priv[0] __aligned(NETDEV_ALIGN);
 };
 
+static inline struct net *wpan_phy_net(struct wpan_phy *wpan_phy)
+{
+	return read_pnet(&wpan_phy->_net);
+}
+
+static inline void wpan_phy_net_set(struct wpan_phy *wpan_phy, struct net *net)
+{
+	write_pnet(&wpan_phy->_net, net);
+}
+
 struct ieee802154_addr {
 	u8 mode;
 	__le16 pan_id;