PM: Avoid calling kfree() under spinlock in dev_pm_put_subsys_data()

Fix dev_pm_put_subsys_data() so that it doesn't call kfree() under
a spinlock and make it return 1 whenever it leaves NULL
power.subsys_data (regardless of the reason).

Signed-off-by: Shuah Khan <shuah.kh@samsung.com>
Reviewed-by: Pavel Machek <pavel@ucw.cz>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>