arm64: dts: mt8173: Power on panel regulator on boot

Add "regulator-boot-on" to "panel_fixed_3v3" to save time on powering
the regulator during boot.  Also add "off-on-delay-us" to the node to
make sure the regulator never violates the panel timing requirements.

Signed-off-by: Pin-yen Lin <treapking@chromium.org>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Link: https://lore.kernel.org/r/20230417123956.926266-1-treapking@chromium.org


Signed-off-by: Matthias Brugger <matthias.bgg@gmail.com>