dt-bindings: phy: Add starfive,jh7110-dphy-tx

StarFive SoCs like the jh7110 use a MIPI D-PHY TX
controller based on a M31 IP. Add a binding for it.

Signed-off-by: Shengyang Chen <shengyang.chen@starfivetech.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20240418035020.47876-2-shengyang.chen@starfivetech.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>