drivers: net: phy: mdio-xgene: Add hardware dependency

The mdio-xgene driver is only useful on X-Gene SoC.

Signed-off-by: Jean Delvare <jdelvare@suse.de>
Cc: Iyappan Subramanian <isubramanian@apm.com>
Cc: David S. Miller <davem@davemloft.net>
Acked-by:  Iyappan Subramanian <isubramanian@apm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/phy/Kconfig

@@ -303,6 +303,7 @@ config MDIO_HISI_FEMAC
 
 config MDIO_XGENE
 	tristate "APM X-Gene SoC MDIO bus controller"
+	depends on ARCH_XGENE || COMPILE_TEST
 	help
 	  This module provides a driver for the MDIO busses found in the
 	  APM X-Gene SoC's.