net: move procfs code to net/core/net-procfs.c

Similar to net/core/net-sysfs.c, group procfs code to
a single 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 0c5e361..b33b996 100644
--- a/net/core/Makefile
+++ b/net/core/Makefile
@@ -13,6 +13,7 @@
 
 obj-$(CONFIG_XFRM) += flow.o
 obj-y += net-sysfs.o
+obj-$(CONFIG_PROC_FS) += net-procfs.o
 obj-$(CONFIG_NET_PKTGEN) += pktgen.o
 obj-$(CONFIG_NETPOLL) += netpoll.o
 obj-$(CONFIG_NET_DMA) += user_dma.o