net: designware: add Amlogic Meson8b & later glue driver

This adds a proper glue driver for the Designware DWMAC ethernet MAC IP
found in the Amlogic Meson8, GXBB, GXL, GXM, G12A, G12B & SM1 SoCs.

This is aimed to replace the static ethernet link setup found on the board
init code for the Amlogic SoC based boards.

Tested on a libretech-cc (S905x Internal RMII 10/100 PHY) and Khadas VIM3 (A113d
with external 10/100/1000 RGMII PHY) to cover the most extreme setups.

Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
diff --git a/drivers/net/Kconfig b/drivers/net/Kconfig
index e1d3b26..cf062fa 100644
--- a/drivers/net/Kconfig
+++ b/drivers/net/Kconfig
@@ -271,6 +271,14 @@
 	  100Mbit and 1 Gbit operation. You must enable CONFIG_PHYLIB to
 	  provide the PHY (physical media interface).
 
+config ETH_DESIGNWARE_MESON8B
+	bool "Amlogic Meson8b and later glue driver for Synopsys Designware Ethernet MAC"
+	depends on DM_ETH
+	select ETH_DESIGNWARE
+	help
+	  This provides glue layer to use Synopsys Designware Ethernet MAC
+	  present on the Amlogic Meson8b, GX, AXG & G12A SoCs.
+
 config ETH_DESIGNWARE_SOCFPGA
 	select REGMAP
 	select SYSCON