phy: qcom-qmp-combo: restructure PHY creation

In preparation for supporting devicetree bindings which do not use child
nodes, move the PHY creation to probe() proper and parse the serdes,
dp_com and dp_serdes resources in a dedicated legacy devicetree helper.

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
Link: https://lore.kernel.org/r/20221121085058.31213-5-johan+linaro@kernel.org


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