drivers: net: add Aspeed MDIO driver

Add a driver for the MDIO interface for Aspeed AST2600 SOC.  The driver
only supports clause 22 for now.

Signed-off-by: Dylan Hung <dylan_hung@aspeedtech.com>
Reviewed-by: Ramon Fried <rfried.dev@gmail.com>
Reviewed-by: Ryan Chen <ryan_chen@aspeedtech.com>
diff --git a/drivers/net/Kconfig b/drivers/net/Kconfig
index 8e9109c..e054bec 100644
--- a/drivers/net/Kconfig
+++ b/drivers/net/Kconfig
@@ -851,6 +851,13 @@
 	  This driver supports the MDIO bus found on the Fman 10G Ethernet MACs and
 	  on the mEMAC (which supports both Clauses 22 and 45).
 
+config ASPEED_MDIO
+	bool "Aspeed MDIO interface support"
+	depends on DM_MDIO
+	help
+	  This driver supports the MDIO bus of Aspeed AST2600 SOC.  The driver
+	  currently supports Clause 22.
+
 config MDIO_MUX_MMIOREG
 	bool "MDIO MUX accessed as a MMIO register access"
 	depends on DM_MDIO_MUX