phy: rockchip: samsung-hdptx: Drop unused phy_cfg driver data

There is no usage of phy_cfg in the upstream driver data, nor in the
downstream one, hence remove it.

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Signed-off-by: Cristian Ciocaltea <cristian.ciocaltea@collabora.com>
Link: https://lore.kernel.org/r/20250318-phy-sam-hdptx-bpc-v6-6-8cb1678e7663@collabora.com


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