Allow the PHY drivers to get the ref clock from the DT. Signed-off-by: Matthias Kaehlcke <mka@chromium.org> Reviewed-by: Stephen Boyd <swboyd@chromium.org> Reviewed-by: Douglas Anderson <dianders@chromium.org> Reviewed-by: Rob Herring <robh@kernel.org> Signed-off-by: Rob Clark <robdclark@gmail.com>