dm: clk: ignore default settings when node not valid

When the device not binded with a node, we need ignore
the parents and rate settings.

Cc: Simon Glass <sjg@chromium.org>
Cc: Jagan Teki <jagan@amarulasolutions.com>
Cc: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
Cc: Neil Armstrong <narmstrong@baylibre.com>
Cc: Andreas Dannenberg <dannenberg@ti.com>
Signed-off-by: Peng Fan <peng.fan@nxp.com>