dt-bindings: serial: 8250_omap: Add wakeup-source property

Add the wakeup-source to enable this device as a wakeup source if
defined in DT.

Signed-off-by: Markus Schneider-Pargmann <msp@baylibre.com>
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Kevin Hilman <khilman@baylibre.com>
Tested-by: Kevin Hilman <khilman@baylibre.com>
Link: https://lore.kernel.org/r/20240807141227.1093006-2-msp@baylibre.com


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