arm64: perf: Use the builtin_platform_driver

Use the builtin_platform_driver() to simplify code.
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

arch/arm64/kernel/perf_event.c

@@ -1057,8 +1057,4 @@ static struct platform_driver armv8_pmu_driver = {
 	.probe		= armv8_pmu_device_probe,
 };
 
-static int __init register_armv8_pmu_driver(void)
-{
-	return platform_driver_register(&armv8_pmu_driver);
-}
-device_initcall(register_armv8_pmu_driver);
+builtin_platform_driver(armv8_pmu_driver);