dt-bindings: rtc: qcom-pm8xxx: allow 'wakeup-source' property

The RTC can be used as a wakeup source on at least some platforms so
allow it to be described as such.

Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
Acked-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20230104095612.6756-1-johan+linaro@kernel.org
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

Documentation/devicetree/bindings/rtc/qcom-pm8xxx-rtc.yaml

@@ -40,6 +40,8 @@ properties:
     description:
       Indicates that the setting of RTC time is allowed by the host CPU.
 
+  wakeup-source: true
+
 required:
   - compatible
   - reg