net: gmac_rockchip: Add Rockchip GMAC driver

Add a new driver for the GMAC ethernet interface present in Rockchip
RK3288 SOCs. This driver subclasses the generic design-ware driver to
add the glue needed specifically for Rockchip.

Signed-off-by: Sjoerd Simons <sjoerd.simons@collabora.co.uk>
Signed-off-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Romain Perier <romain.perier@collabora.com>
Acked-by: Joe Hershberger <joe.hershberger@ni.com>
diff --git a/drivers/net/Kconfig b/drivers/net/Kconfig
index 929b9e2..f52629f 100644
--- a/drivers/net/Kconfig
+++ b/drivers/net/Kconfig
@@ -215,4 +215,11 @@
 	  This driver implements 10/100 Mbps Ethernet and MAC layer for
 	  Microchip PIC32 microcontrollers.
 
+config GMAC_ROCKCHIP
+	bool "Rockchip Synopsys Designware Ethernet MAC"
+	depends on DM_ETH && ETH_DESIGNWARE
+	help
+	  This driver provides Rockchip SoCs network support based on the
+	  Synopsys Designware driver.
+
 endif # NETDEVICES