device property: fix of node refcount leak in fwnode_graph_get_next_endpoint()

The 'parent' returned by fwnode_graph_get_port_parent()
with refcount incremented when 'prev' is not NULL, it
needs be put when finish using it.

Because the parent is const, introduce a new variable to
store the returned fwnode, then put it before returning
from fwnode_graph_get_next_endpoint().

Fixes: b5b41ab6

 ("device property: Check fwnode->secondary in fwnode_graph_get_next_endpoint()")
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Reviewed-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-and-tested-by: Daniel Scally <djrscally@gmail.com>
Link: https://lore.kernel.org/r/20221123022542.2999510-1-yangyingliang@huawei.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>