ARM: dts: rockchip: Fix supply node for card's power on phycore som

The card is powered by the RK818 switch vdd_sd which is supplied
by VCC9 (VDD_3V3_IO).

Signed-off-by: Wadim Egorov <w.egorov@phytec.de>
Signed-off-by: Daniel Schultz <d.schultz@phytec.de>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>