phy: adin: add driver for Analog Devices ADIN1300 PHY

The current implementation configures RGMII using device tree phy-mode
property and then calls genphy_config

adin_config_rgmii_mode is derived from:
https://github.com/varigit/linux-imx/blob/lf-5.10.y_var04/drivers/net/phy/adin.c#L218-L262

Signed-off-by: Nate Drude <nate.d@variscite.com>
Reviewed-by: Ramon Fried <rfried.dev@gmail.com>
diff --git a/drivers/net/phy/Kconfig b/drivers/net/phy/Kconfig
index 014a4de..2f90ab0 100644
--- a/drivers/net/phy/Kconfig
+++ b/drivers/net/phy/Kconfig
@@ -68,6 +68,11 @@
 config PHYLIB_10G
 	bool "Generic 10G PHY support"
 
+config PHY_ADIN
+	bool "Analog Devices Industrial Ethernet PHYs"
+	help
+		Add support for configuring RGMII on Analog Devices ADIN PHYs.
+
 menuconfig PHY_AQUANTIA
 	bool "Aquantia Ethernet PHYs support"
 	select PHY_GIGE