arm64: dts: rockchip: define cpu-supply on the Qnap-TS433

The TS433 seems to use a silergy,syr827 regulator for the cpu supply.
At least that is the compatible used in the vendor devicetree, though
it could very well also be another fan53555 clone.

Define the needed regulator node and hook up the cpu-supply to the
cpu cores.

Tested-by: Uwe Kleine-König <ukleinek@debian.org>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Link: https://lore.kernel.org/r/20240723195538.1133436-12-heiko@sntech.de