ieee820154: add lbt setting support

This patch adds support for setting listen before transmit mode via
nl802154 framework.

Signed-off-by: Alexander Aring <alex.aring@gmail.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
diff --git a/include/net/cfg802154.h b/include/net/cfg802154.h
index 5c3bc12..fa0a9e5 100644
--- a/include/net/cfg802154.h
+++ b/include/net/cfg802154.h
@@ -51,6 +51,8 @@
 	int	(*set_max_frame_retries)(struct wpan_phy *wpan_phy,
 					 struct wpan_dev *wpan_dev,
 					 s8 max_frame_retries);
+	int	(*set_lbt_mode)(struct wpan_phy *wpan_phy,
+				struct wpan_dev *wpan_dev, bool mode);
 };
 
 struct wpan_phy {