cpuidle: big.LITTLE: add of_device_id structure

This driver will be used by many big.Little Soc's. As of now it does
string matching of hardcoded compatible string to init the driver. This
comparison list will keep on growing with addition of new SoC's.
Hence add of_device_id structure to collect the compatible strings of
SoC's using this driver.

Signed-off-by: Chander Kashyap <chander.kashyap@linaro.org>
Reviewed-by: Tomasz Figa <t.figa@samsung.com>
Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>

drivers/cpuidle/cpuidle-big_little.c

@@ -163,14 +163,23 @@ static int __init bl_idle_driver_init(struct cpuidle_driver *drv, int cpu_id)
 	return 0;
 }
 
+static const struct of_device_id compatible_machine_match[] = {
+	{ .compatible = "arm,vexpress,v2p-ca15_a7" },
+	{},
+};
+
 static int __init bl_idle_init(void)
 {
 	int ret;
+	struct device_node *root = of_find_node_by_path("/");
+
+	if (!root)
+		return -ENODEV;
 
 	/*
 	 * Initialize the driver just for a compliant set of machines
 	 */
-	if (!of_machine_is_compatible("arm,vexpress,v2p-ca15_a7"))
+	if (!of_match_node(compatible_machine_match, root))
 		return -ENODEV;
 	/*
 	 * For now the differentiation between little and big cores