dt-bindings: pinctrl: mt65xx: Allow gpio-line-names

dt-bindings: pinctrl: mt65xx: Allow gpio-line-names

Current, the DT bindings for MediaTek's MT65xx Pin controller is missing
the gpio-line-names property, add it to the associated schema.

Signed-off-by: Ariel D'Alessandro <ariel.dalessandro@collabora.com>
Acked-by: Rob Herring (Arm) <robh@kernel.org>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Rob Herring (Arm) <robh@kernel.org>