device property: preserve usecount for node passed to of_fwnode_graph_get_port_parent()

device property: preserve usecount for node passed to of_fwnode_graph_get_port_parent()

Using CONFIG_OF_DYNAMIC=y uncovered an imbalance in the usecount of the
node being passed to of_fwnode_graph_get_port_parent(). Preserve the
usecount by using of_get_parent() instead of of_get_next_parent() which
don't decrement the usecount of the node passed to it.

Fixes: 3b27d00e7b6d7c88 ("device property: Move fwnode graph ops to firmware specific locations")
Signed-off-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Acked-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Rob Herring <robh@kernel.org>