dt-bindings: pinctrl: mediatek,mt6779-pinctrl: Make gpio-ranges optional

The pin controller can function without specifying gpio-ranges so remove
it from required properties. This is also done in preparation for adding
other pin controllers which currently don't have the gpio-ranges property
defined where they are used in DTS. This allows dtbs_check to pass on
those device trees.

Signed-off-by: Yassine Oudjana <[e-mail]>
Reviewed-by: Rob Herring <[e-mail]>
Reviewed-by: AngeloGioacchino Del Regno <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Linus Walleij <[e-mail]>

Documentation/devicetree/bindings/pinctrl/mediatek,mt6779-pinctrl.yaml

···
   - reg-names
   - gpio-controller
   - "#gpio-cells"
-  - gpio-ranges
   - interrupt-controller
   - interrupts
   - "#interrupt-cells"