arm64: dts: mediatek: mt8173-elm-hana: Add vdd-supply to second source trackpad

The Hana device has a second source option trackpad, but it is missing
its regulator supply. It only works because the regulator is marked as
always-on.

Add the regulator supply, but leave out the post-power-on delay. Instead,
document the post-power-on delay along with the reason for not adding
it in a comment.

Fixes: 689b937b ("arm64: dts: mediatek: add mt8173 elm and hana board")
Signed-off-by: Chen-Yu Tsai <wenst@chromium.org>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Link: https://lore.kernel.org/r/20241018082001.1296963-1-wenst@chromium.org


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