arm64: dts: rockchip: add pd_sd power-domain node for rk3399

Add the sd power-domain, its qos area and assign it to the
sdmmc device node.

Signed-off-by: Elaine Zhang <zhangqing@rock-chips.com>
Signed-off-by: Caesar Wang <wxt@rock-chips.com>
Tested-by: Shawn Lin <shawn.lin@rock-chips.com>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>