platform/surface: aggregator: Use serdev_acpi_get_uart_resource() helper

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.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>