ARM: dts: rockchip: add input supplies for the act8846 on Radxa Rock

On the Radxa Rock board most supplies come from the static 5v vsys supply, but
the inl1-supply comes from the REG4 of the act8846 itself. Model this dependency
using the added supply-handling to make sure the supplying regulator gets handled
correctly and not accidentially turned off.

Signed-off-by: Heiko Stuebner <heiko@sntech.de>