net: move ioctl functions into a separated file

They well deserve a separated unit.

Cc: "David S. Miller" <davem@davemloft.net>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/core/Makefile b/net/core/Makefile
index 674641b..0c5e361 100644
--- a/net/core/Makefile
+++ b/net/core/Makefile
@@ -9,7 +9,7 @@
 
 obj-y		     += dev.o ethtool.o dev_addr_lists.o dst.o netevent.o \
 			neighbour.o rtnetlink.o utils.o link_watch.o filter.o \
-			sock_diag.o
+			sock_diag.o dev_ioctl.o
 
 obj-$(CONFIG_XFRM) += flow.o
 obj-y += net-sysfs.o