ACPI / PM: Fix unused function warnings for CONFIG_PM_SLEEP

According to compiler warnings, several suspend/resume functions
in ACPI drivers are not used for CONFIG_PM_SLEEP unset, so add
#ifdefs to prevent them from being built in that case.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>

drivers/acpi/thermal.c

@@ -106,7 +106,9 @@ static const struct acpi_device_id  thermal_device_ids[] = {
 };
 MODULE_DEVICE_TABLE(acpi, thermal_device_ids);
 
+#ifdef CONFIG_PM_SLEEP
 static int acpi_thermal_resume(struct device *dev);
+#endif
 static SIMPLE_DEV_PM_OPS(acpi_thermal_pm, NULL, acpi_thermal_resume);
 
 static struct acpi_driver acpi_thermal_driver = {
@@ -1041,6 +1043,7 @@ static int acpi_thermal_remove(struct acpi_device *device, int type)
 	return 0;
 }
 
+#ifdef CONFIG_PM_SLEEP
 static int acpi_thermal_resume(struct device *dev)
 {
 	struct acpi_thermal *tz;
@@ -1075,6 +1078,7 @@ static int acpi_thermal_resume(struct device *dev)
 
 	return AE_OK;
 }
+#endif
 
 static int thermal_act(const struct dmi_system_id *d) {