cpufreq: mediatek: Unregister platform device on exit

We register the platform device when driver inits. However, we do not
unregister it when driver exits.

To resolve this, we declare the platform data to be a global static
variable and rename it to be "cpufreq_pdev". With this global variable,
we can do platform_device_unregister() when driver exits.

Fixes: 501c574 ("cpufreq: mediatek: Add support of cpufreq to MT2701/MT7623 SoC")
Signed-off-by: Rex-BC Chen <rex-bc.chen@mediatek.com>
[ Viresh: Commit log and Subject ]
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>

Author: mtk-rex-bc-chen

drivers/cpufreq/mediatek-cpufreq.c

@@ -43,6 +43,8 @@ struct mtk_cpu_dvfs_info {
 	int pre_vproc;
 };
 
+static struct platform_device *cpufreq_pdev;
+
 static LIST_HEAD(dvfs_info_list);
 
 static struct mtk_cpu_dvfs_info *mtk_cpu_dvfs_info_lookup(int cpu)
@@ -578,7 +580,6 @@ static int __init mtk_cpufreq_driver_init(void)
 {
 	struct device_node *np;
 	const struct of_device_id *match;
-	struct platform_device *pdev;
 	int err;
 
 	np = of_find_node_by_path("/");
@@ -602,11 +603,11 @@ static int __init mtk_cpufreq_driver_init(void)
 	 * and the device registration codes are put here to handle defer
 	 * probing.
 	 */
-	pdev = platform_device_register_simple("mtk-cpufreq", -1, NULL, 0);
-	if (IS_ERR(pdev)) {
+	cpufreq_pdev = platform_device_register_simple("mtk-cpufreq", -1, NULL, 0);
+	if (IS_ERR(cpufreq_pdev)) {
 		pr_err("failed to register mtk-cpufreq platform device\n");
 		platform_driver_unregister(&mtk_cpufreq_platdrv);
-		return PTR_ERR(pdev);
+		return PTR_ERR(cpufreq_pdev);
 	}
 
 	return 0;
@@ -615,6 +616,7 @@ module_init(mtk_cpufreq_driver_init)
 
 static void __exit mtk_cpufreq_driver_exit(void)
 {
+	platform_device_unregister(cpufreq_pdev);
 	platform_driver_unregister(&mtk_cpufreq_platdrv);
 }
 module_exit(mtk_cpufreq_driver_exit)