ACPI: introduce helper function acpi_execute_simple_method()

Introduce helper function acpi_execute_simple_method() and use it in
a number of places to simplify code.

[rjw: Changelog]
Signed-off-by: Jiang Liu <jiang.liu@huawei.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
diff --git a/drivers/acpi/sleep.c b/drivers/acpi/sleep.c
index 187ab61..81b0f03 100644
--- a/drivers/acpi/sleep.c
+++ b/drivers/acpi/sleep.c
@@ -31,12 +31,9 @@
 
 static void acpi_sleep_tts_switch(u32 acpi_state)
 {
-	union acpi_object in_arg = { ACPI_TYPE_INTEGER };
-	struct acpi_object_list arg_list = { 1, &in_arg };
-	acpi_status status = AE_OK;
+	acpi_status status;
 
-	in_arg.integer.value = acpi_state;
-	status = acpi_evaluate_object(NULL, "\\_TTS", &arg_list, NULL);
+	status = acpi_execute_simple_method(NULL, "\\_TTS", acpi_state);
 	if (ACPI_FAILURE(status) && status != AE_NOT_FOUND) {
 		/*
 		 * OS can't evaluate the _TTS object correctly. Some warning