ACPI / property: Document RS485 _DSD properties

Document RS485 related properties returned from ACPI _DSD as device
properties.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20220426122448.38997-5-ilpo.jarvinen@linux.intel.com


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