arm64: dts: rockchip: Add PHY node for HDMI1 TX port on RK3588

arm64: dts: rockchip: Add PHY node for HDMI1 TX port on RK3588

In preparation to enable the second HDMI output port found on RK3588
SoC, add the related PHY node.  This requires a GRF, hence add the
dependent node as well.

Signed-off-by: Cristian Ciocaltea <cristian.ciocaltea@collabora.com>
Tested-by: Jagan Teki <jagan@edgeble.ai> # edgeble-6tops-modules
Tested-by: Alexandre ARNOUD <aarnoud@me.com>
Link: https://lore.kernel.org/r/20241211-rk3588-hdmi1-v2-2-02cdca22ff68@collabora.com
Signed-off-by: Heiko Stuebner <heiko@sntech.de>