dt-bindings: power: reset: gpio-poweroff: Add priority property

Add the priority property to the gpio-poweroff bindings description.

Signed-off-by: Stefan Eichenberger <stefan.eichenberger@toradex.com>
Signed-off-by: Francesco Dolcini <francesco.dolcini@toradex.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20231006130428.11259-4-francesco@dolcini.it


Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>