net: add Amlogic Meson G12A MDIO MUX driver

The Amlogic G12A & compatible SoCs embeds a mux to either communicate with
the external PHY or the internal 10/100 PHY.

This adds support for this mux as a MDIO MUX device.

Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Reviewed-by: Ramon Fried <rfried.dev@gmail.com>
diff --git a/drivers/net/Kconfig b/drivers/net/Kconfig
index 41fa2fe..e1d3b26 100644
--- a/drivers/net/Kconfig
+++ b/drivers/net/Kconfig
@@ -797,4 +797,11 @@
 	  This driver is used for MDIO muxes driven by writing to a register in
 	  the MMIO physical memory.
 
+config MDIO_MUX_MESON_G12A
+	bool "MDIO MUX for Amlogic Meson G12A SoCs"
+	depends on DM_MDIO_MUX
+	help
+	  This driver is used for the MDIO mux found on the Amlogic G12A & compatible
+	  SoCs.
+
 endif # NETDEVICES