dt-bindings: gce: add the GCE header file for MT8186

Add the GCE header file to define GCE subsys ids, hardware event ids
and constants for MT8186.

Signed-off-by: Yongqiang Niu <yongqiang.niu@mediatek.com>
Acked-by: Rob Herring <robh@kernel.org>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Signed-off-by: Jassi Brar <jaswinder.singh@linaro.org>