ieee802154: rename af_ieee802154.c to socket.c

This patch renames the "af_ieee802154.c" to "socket.c". This is just a
cleanup to have a short name for it which describes the implementationm
stuff more human understandable.
Signed-off-by: NAlexander Aring <alex.aring@gmail.com>
Signed-off-by: NMarcel Holtmann <marcel@holtmann.org>

net/ieee802154/Makefile

@@ -5,6 +5,6 @@ obj-$(CONFIG_IEEE802154_6LOWPAN) += ieee802154_6lowpan.o
 ieee802154_6lowpan-y := 6lowpan_rtnl.o reassembly.o
 ieee802154-y := netlink.o nl-mac.o nl-phy.o nl_policy.o core.o \
                 header_ops.o sysfs.o nl802154.o
-ieee802154_socket-y := af_ieee802154.o
+ieee802154_socket-y := socket.o
 
 ccflags-y += -D__CHECK_ENDIAN__