net: Move common init into a new eth_common.c file

Only half of the init is actually common. Move that part into a new common
file and call it from driver-model and legacy code. More common functions
will be added in future patches.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Acked-by: Joe Hershberger <joe.hershberger@ni.com>
diff --git a/net/Makefile b/net/Makefile
index e9cc8ad..b3a22c2 100644
--- a/net/Makefile
+++ b/net/Makefile
@@ -13,6 +13,7 @@
 obj-$(CONFIG_CMD_CDP)  += cdp.o
 obj-$(CONFIG_CMD_DNS)  += dns.o
 obj-$(CONFIG_CMD_NET)  += eth.o
+obj-$(CONFIG_CMD_NET)  += eth_common.o
 obj-$(CONFIG_CMD_LINK_LOCAL) += link_local.o
 obj-$(CONFIG_CMD_NET)  += net.o
 obj-$(CONFIG_CMD_NFS)  += nfs.o