arm64: dts: rockchip: enable uart0 on Qnap-TS433

arm64: dts: rockchip: enable uart0 on Qnap-TS433

Uart0 is connected to an MCU on the board that handles system control
like the fan-speed. So far no driver for it is available though.

Tested-by: Uwe Kleine-König <ukleinek@debian.org>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Link: https://lore.kernel.org/r/20240723195538.1133436-4-heiko@sntech.de
[ upstream commit: 07ef8be476bebd77cba3ca4804be03cc0dba414f ]

(cherry picked from commit aaa5b1c4bd8f0e4327078d513f0eef05cb829bcf)
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>