cpuidle: psci: Move initialization a bit earlier in the boot sequence

When using PSCI OS-initiated mode along with the cpuidle-psci-domain driver
it's of great benefit to attach the CPU devices to their CPU PM domains as
soon as possible, as other non-CPU devices sharing the same PM domains
depends on it to allow their devices to be probed.

Let's therefore move to a subsys_initcall, which should be soon enough
after the cpuidle-psci-domain have initialized the PM domain topology.

Reviewed-by: Abel Vesa <abel.vesa@oss.qualcomm.com>
Tested-by: Yuanfang Zhang <yuanfang.zhang@oss.qualcomm.com>
Signed-off-by: Ulf Hansson <ulf.hansson@oss.qualcomm.com>
Reviewed-by: Dhruva Gole <goledhruva@gmail.com>
Signed-off-by: Ulf Hansson <ulfh@kernel.org>

drivers/cpuidle/cpuidle-psci.c

@@ -479,4 +479,4 @@ static int __init psci_idle_init(void)
 
 	return 0;
 }
-device_initcall(psci_idle_init);
+subsys_initcall(psci_idle_init);