ACPI: scan: Turn off unused power resources during initialization

It is reported that on certain platforms there are power resources
that are not associated with any devices physically present in the
platform. Those power resources are expected to be turned off by
the OS in accordance with the ACPI specification (section 7.3 of
ACPI 6.4) which currently is not done by Linux and that may lead
to obscure issues.

For instance, leaving those power resources in the "on" state may
prevent the platform from reaching the lowest power state in
suspend-to-idle which leads to excessive power draw.

For this reason, turn all of the unused ACPI power resources off
at the end of the initial namespace scan for devices in analogy with
resume from suspend-to-RAM.

Link: https://uefi.org/specs/ACPI/6.4/07_Power_and_Performance_Mgmt/device-power-management-objects.html
Reported-by: David Box <[e-mail]>
Tested-by: Wendy Wang <[e-mail]>
Signed-off-by: Rafael J. Wysocki <[e-mail]>

drivers/acpi/internal.h

···
 int acpi_power_get_inferred_state(struct acpi_device *device, int *state);
 int acpi_power_on_resources(struct acpi_device *device, int state);
 int acpi_power_transition(struct acpi_device *device, int state);
+void acpi_turn_off_unused_power_resources(void);
 
 /* --------------------------------------------------------------------------
                               Device Power Management

drivers/acpi/power.c

···
 
 	mutex_unlock(&power_resource_list_lock);
 }
+#endif
 
 void acpi_turn_off_unused_power_resources(void)
 {
···
 
 	mutex_unlock(&power_resource_list_lock);
 }
-#endif

drivers/acpi/scan.c

···
 		}
 	}
 
+	acpi_turn_off_unused_power_resources();
+
 	acpi_scan_initialized = true;
 
  out:

drivers/acpi/sleep.h

···
 extern struct mutex acpi_device_lock;
 
 extern void acpi_resume_power_resources(void);
-extern void acpi_turn_off_unused_power_resources(void);
 
 static inline acpi_status acpi_set_waking_vector(u32 wakeup_address)
 {