dt-bindings: arm: mediatek: Add MT8186 Ponyta Chromebook

Ponyta is a custom label Chromebook based on MT8186. It is a
self-developed project of Huaqin and has no fixed OEM.

Signed-off-by: Jianeng Ceng <cengjianeng@huaqin.corp-partner.google.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20250424010850.994288-2-cengjianeng@huaqin.corp-partner.google.com


Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>