drivers/ieee802154: IEEE 802.15.4 loopback driver

Add support for IEEE 802.15.4 loopback driver - useful development
and debugging tool.

Signed-off-by: Alexander Smirnov <alex.bluesman.smirnov@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/ieee802154/Makefile b/drivers/ieee802154/Makefile
index 800a389..ea784ea 100644
--- a/drivers/ieee802154/Makefile
+++ b/drivers/ieee802154/Makefile
@@ -1 +1,2 @@
 obj-$(CONFIG_IEEE802154_FAKEHARD) += fakehard.o
+obj-$(CONFIG_IEEE802154_FAKELB) += fakelb.o