serdev: Split and export serdev_acpi_get_uart_resource()

The same as for I²C Serial Bus resource split and export
serdev_acpi_get_uart_resource(). We have already a few users
one of which is converted here.

Rationale of this is to consolidate parsing UART Serial Bus
resource in one place as it's done, e.g., for I²C Serial Bus.

Reviewed-by: Hans de Goede <hdegoede@redhat.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/20210806111736.66591-1-andriy.shevchenko@linux.intel.com


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