ACPI: dock: convert acpi_evaluate_object() to acpi_evaluate_integer()

acpi_evaluate_integer() is an ACPI API introduced to evaluate an
ACPI control method that is known to have an integer return value.
This API can simplify the code because the calling function does not need to
use the specified acpi_buffer structure required by acpi_evaluate_object();

Convert acpi_evaluate_object() to acpi_evaluate_integer()
in drivers/acpi/dock.c in this patch.
Signed-off-by: Zhang Rui <rui.zhang@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/acpi/dock.c

@@ -441,7 +441,7 @@ static void handle_dock(struct dock_station *ds, int dock)
 	acpi_status status;
 	struct acpi_object_list arg_list;
 	union acpi_object arg;
-	struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
+	unsigned long long value;
 
 	acpi_handle_info(ds->handle, "%s\n", dock ? "docking" : "undocking");
 
@@ -450,12 +450,10 @@ static void handle_dock(struct dock_station *ds, int dock)
 	arg_list.pointer = &arg;
 	arg.type = ACPI_TYPE_INTEGER;
 	arg.integer.value = dock;
-	status = acpi_evaluate_object(ds->handle, "_DCK", &arg_list, &buffer);
+	status = acpi_evaluate_integer(ds->handle, "_DCK", &arg_list, &value);
 	if (ACPI_FAILURE(status) && status != AE_NOT_FOUND)
 		acpi_handle_err(ds->handle, "Failed to execute _DCK (0x%x)\n",
 				status);
-
-	kfree(buffer.pointer);
 }
 
 static inline void dock(struct dock_station *ds)