phy: qcom-qmp-usb: drop sc8280xp reference-clock source

The source clock for the reference clock is not used by the PHY directly
and should not be described by the devicetree (instead this relationship
should be modelled in the clock driver).

Drop the driver management of the reference-clock source for SC8280XP.

Once the other clock drivers have been updated, the corresponding change
can be done also for the other QMP v4 platforms.

Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Reviewed-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20221111093857.11360-3-johan+linaro@kernel.org


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