drivers: net: xgene: constify of_device_id array

of_device_id is always used as const.
(See driver.of_match_table and open firmware functions)
Signed-off-by: Fabian Frederick <fabf@skynet.be>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/apm/xgene/xgene_enet_main.c

@@ -1033,7 +1033,7 @@ MODULE_DEVICE_TABLE(acpi, xgene_enet_acpi_match);
 #endif
 
 #ifdef CONFIG_OF
-static struct of_device_id xgene_enet_of_match[] = {
+static const struct of_device_id xgene_enet_of_match[] = {
 	{.compatible = "apm,xgene-enet",},
 	{.compatible = "apm,xgene1-sgenet",},
 	{.compatible = "apm,xgene1-xgenet",},