drivers: net: Kconfig: Add PHY_MICREL_KSZ9021 entry

Add kconfig entry for Micrel KSZ9021 PHY support.

Cc: Joe Hershberger <joe.hershberger@ni.com>
Signed-off-by: Jagan Teki <jagan@amarulasolutions.com>
diff --git a/drivers/net/phy/Kconfig b/drivers/net/phy/Kconfig
index aca3990..ce1b30a 100644
--- a/drivers/net/phy/Kconfig
+++ b/drivers/net/phy/Kconfig
@@ -58,6 +58,14 @@
 config PHY_MICREL
 	bool "Micrel Ethernet PHYs support"
 
+config PHY_MICREL_KSZ9021
+	bool "Micrel KSZ9021 Ethernet PHYs support"
+	depends on PHY_MICREL
+	help
+          KSZ9021 is a completely integrated triple speed (10Base-T/100Base-TX/1000Base-T)
+	  Ethernet Physical Layer Transceiver for transmission and reception of data over
+	  standard CAT-5 unshielded twisted pair (UTP) cable.
+
 config PHY_MSCC
 	bool "Microsemi Corp Ethernet PHYs support"