arm64: dts: mediatek: mt8192: Add missing gce-client-reg to mutex

Add the missing mediatek,gce-client-reg property to the mutex node to
allow it to use the GCE. This prevents the "can't parse gce-client-reg
property" error from being printed and should result in better
performance.

Fixes: b4b75bac

 ("arm64: dts: mt8192: Add display nodes")
Suggested-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Signed-off-by: Nícolas F. R. A. Prado <nfraprado@collabora.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Link: https://lore.kernel.org/r/20240229-gce-client-reg-add-missing-mt8192-95-v1-1-b12c233a8a33@collabora.com


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