cpufreq: loongson2: Unregister platform_driver on failure

When cpufreq_register_driver() returns error, the cpufreq_init() returns
without unregister platform_driver, fix by add missing
platform_driver_unregister() when cpufreq_register_driver() failed.

Fixes: f8ede0f ("MIPS: Loongson 2F: Add CPU frequency scaling support")
Signed-off-by: Yuan Can <yuancan@huawei.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>

drivers/cpufreq/loongson2_cpufreq.c

@@ -148,7 +148,9 @@ static int __init cpufreq_init(void)
 
 	ret = cpufreq_register_driver(&loongson2_cpufreq_driver);
 
-	if (!ret && !nowait) {
+	if (ret) {
+		platform_driver_unregister(&platform_driver);
+	} else if (!nowait) {
 		saved_cpu_wait = cpu_wait;
 		cpu_wait = loongson2_cpu_wait;
 	}