arm64: dts: rockchip: Provide emmcclk to PHY for rk3399

Previous changes in this series allowed exposing the card clock from the
rk3399 SDHCI device and allowed consuming the card clock in the rk3399
eMMC PHY.  Hook things up in the main rk3399 dtsi file.

Signed-off-by: Douglas Anderson <dianders@chromium.org>
Tested-by: Heiko Stuebner <heiko@sntech.de>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>