net: xgene_enet: Set hardware dependency

The xgene_enet driver is only useful on X-Gene SoC.
Signed-off-by: Jean Delvare <jdelvare@suse.de>
Cc: Iyappan Subramanian <isubramanian@apm.com>
Cc: Keyur Chudgar <kchudgar@apm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/apm/xgene/Kconfig

 config NET_XGENE
 	tristate "APM X-Gene SoC Ethernet Driver"
 	depends on HAS_DMA
+	depends on ARCH_XGENE || COMPILE_TEST
 	select PHYLIB
 	help
 	  This is the Ethernet driver for the on-chip ethernet interface on the