dt-bindings: phy: rockchip: Add missing "phy-supply" property

Several Rockchip PHYs use the "phy-supply" property, but don't
document it. Add it to the current known users.

Signed-off-by: Rob Herring (Arm) <robh@kernel.org>
Reviewed-by: Heiko Stuebner <heiko@sntech.de>
Link: https://lore.kernel.org/r/20250407165607.2937088-1-robh@kernel.org


Signed-off-by: Vinod Koul <vkoul@kernel.org>