ieee802154: handle socket functionality as module

This patch makes the ieee802154 socket handling as module. Currently
this is part of ieee802154 module. It pointed out that ieee802154 module
has also two module_init/module_exit functions. One inside of core.c and
the other in af_ieee802154.c. This patch will also solve this issue by
handle the af_802154 as separate module.
Signed-off-by: Alexander Aring <alex.aring@gmail.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

net/ieee802154/Kconfig

@@ -10,6 +10,15 @@ config IEEE802154
 	  Say Y here to compile LR-WPAN support into the kernel or say M to
 	  compile it as modules.
 
+config IEEE802154_SOCKET
+	tristate "IEEE 802.15.4 socket interface"
+	depends on IEEE802154
+	default y
+	---help---
+	  Socket interface for IEEE 802.15.4. Contains DGRAM sockets interface
+	  for 802.15.4 dataframes. Also RAW socket interface to build MAC
+	  header from userspace.
+
 config IEEE802154_6LOWPAN
 	tristate "6lowpan support over IEEE 802.15.4"
 	depends on IEEE802154 && 6LOWPAN

net/ieee802154/Makefile

-obj-$(CONFIG_IEEE802154) += ieee802154.o af_802154.o
+obj-$(CONFIG_IEEE802154) += ieee802154.o
+obj-$(CONFIG_IEEE802154_SOCKET) += af_802154.o
 obj-$(CONFIG_IEEE802154_6LOWPAN) += ieee802154_6lowpan.o
 
 ieee802154_6lowpan-y := 6lowpan_rtnl.o reassembly.o