platform/surface: aggregator: Use serdev_acpi_get_uart_resource() helper

serdev provides a generic helper to get UART Serial Bus resources.
Use it instead of an open coded variant.
Reviewed-by: Maximilian Luz <luzmaximilian@gmail.com>
Acked-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20210806111736.66591-2-andriy.shevchenko@linux.intel.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/platform/surface/aggregator/core.c

@@ -301,20 +301,13 @@ static acpi_status ssam_serdev_setup_via_acpi_crs(struct acpi_resource *rsc,
 						  void *ctx)
 {
 	struct serdev_device *serdev = ctx;
-	struct acpi_resource_common_serialbus *serial;
 	struct acpi_resource_uart_serialbus *uart;
 	bool flow_control;
 	int status = 0;
 
-	if (rsc->type != ACPI_RESOURCE_TYPE_SERIAL_BUS)
+	if (!serdev_acpi_get_uart_resource(rsc, &uart))
 		return AE_OK;
 
-	serial = &rsc->data.common_serial_bus;
-	if (serial->type != ACPI_RESOURCE_SERIAL_TYPE_UART)
-		return AE_OK;
-
-	uart = &rsc->data.uart_serial_bus;
-
 	/* Set up serdev device. */
 	serdev_device_set_baudrate(serdev, uart->default_baud_rate);