dm: eth: Add basic driver model support to Ethernet stack

First just add support for MAC drivers.

Signed-off-by: Joe Hershberger <joe.hershberger@ni.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/net/Kconfig b/drivers/net/Kconfig
index e69de29..94cf099 100644
--- a/drivers/net/Kconfig
+++ b/drivers/net/Kconfig
@@ -0,0 +1,9 @@
+config DM_ETH
+	bool "Enable Driver Model for Ethernet drivers"
+	depends on DM
+	help
+	  Enable driver model for Ethernet.
+
+	  The eth_*() interface will be implemented by the UC_ETH class
+	  This is currently implemented in net/eth.c
+	  Look in include/net.h for details.