dt-bindings: power: Clarify wording for wakeup-source property

The wording in the current documentation is a little strong. The
intention was not to fix any particular interrupt as wakeup capable but
leave those details to the device. It wasn't intended to enforce any
rules as what can be or can't be a wakeup interrupt.

Soften the wording to not mandate that the 'wakeup-source' property be
used, and clarify what it means when an interrupt is marked (or not
marked) for wakeup.

Link: https://lore.kernel.org/all/ZYAjxxHcCOgDVMTQ@bogus/
Link: https://lore.kernel.org/all/CAL_Jsq+MYwOG40X26cYmO9EkZ9xqWrXDi03MaRfxnV-+VGkXWQ@mail.gmail.com/


Signed-off-by: Mark Hasemeyer <markhas@chromium.org>
Link: https://lore.kernel.org/r/20240102140734.v4.4.I1016a45ac9e8daf8a9ebc9854ab90ec3542e7c30@changeid


Signed-off-by: Rob Herring <robh@kernel.org>