net: stm32: add designware mac glue code for stm32

This patch adds glue code required for enabling the designware
mac on stm32f7 devices.

Signed-off-by: Michael Kurz <michi.kurz@gmail.com>
Acked-by: Joe Hershberger <joe.hershberger@ni.com>

drivers/net/designware.c

@@ -763,6 +763,7 @@ static const struct udevice_id designware_eth_ids[] = {
 	{ .compatible = "allwinner,sun7i-a20-gmac" },
 	{ .compatible = "altr,socfpga-stmmac" },
 	{ .compatible = "amlogic,meson6-dwmac" },
+	{ .compatible = "st,stm32-dwmac" },
 	{ }
 };