mac802154: add get short address method

Add method to get the device short 802.15.4 address. This call
needed by ieee802154 layer to satisfy 'iz list' request from
the user space.

Signed-off-by: Alexander Smirnov <alex.bluesman.smirnov@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/mac802154/mac802154.h b/net/mac802154/mac802154.h
index 6967864..a4dcaf1 100644
--- a/net/mac802154/mac802154.h
+++ b/net/mac802154/mac802154.h
@@ -109,6 +109,7 @@
 
 /* MIB callbacks */
 void mac802154_dev_set_short_addr(struct net_device *dev, u16 val);
+u16 mac802154_dev_get_short_addr(const struct net_device *dev);
 void mac802154_dev_set_ieee_addr(struct net_device *dev);
 u16 mac802154_dev_get_pan_id(const struct net_device *dev);
 void mac802154_dev_set_pan_id(struct net_device *dev, u16 val);