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: 689b937bedde ("arm64: dts: mediatek: add mt8173 elm and hana board")
Signed-off-by: Chen-Yu Tsai <wenst@xxxxxxxxxxxx>