ieee802154: add wpan_phy dump support

This patch adds support for dumping wpan_phy attributes via nl802154.

Signed-off-by: Alexander Aring <alex.aring@gmail.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
diff --git a/net/ieee802154/core.h b/net/ieee802154/core.h
index c8319bf..f3e9558 100644
--- a/net/ieee802154/core.h
+++ b/net/ieee802154/core.h
@@ -36,6 +36,7 @@
 }
 
 extern struct list_head cfg802154_rdev_list;
+extern int cfg802154_rdev_list_generation;
 
 /* free object */
 void cfg802154_dev_free(struct cfg802154_registered_device *rdev);