rockchip: rk3399-evb: add stdout-path for the board

The 'stdout-path' is missing after dts sync.
Fixes: 167efc2c7a ("arm64: dts: rk3399: Sync v5.7-rc1 from Linux")

Signed-off-by: Kever Yang <kever.yang@rock-chips.com>
1 file changed