phy: qcom-qmp-combo: drop start and pwrdn-ctrl abstraction

All USB PHYs need to start and stop the SerDes and PCS so drop the
start-ctrl abstraction which is no longer needed since the QMP driver
split.

Similarly, drop the pwrdn-ctrl abstraction which also is not needed
since the split.

Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Link: https://lore.kernel.org/r/20221012085002.24099-15-johan+linaro@kernel.org


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