dt-bindings: mfd: syscon: Add rk3588 QoS register compatible

Document rk3588 compatible for QoS registers.

Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>
Reviewed-by: Heiko Stuebner <heiko@sntech.de>
Signed-off-by: Lee Jones <lee@kernel.org>
Link: https://lore.kernel.org/r/20220906143825.199089-5-sebastian.reichel@collabora.com