of: unittest: fix use-after-free in testdrv_probe()

In the Linux kernel, the following vulnerability has been resolved:

of: unittest: fix use-after-free in testdrv_probe()

The function testdrv_probe() retrieves the device_node from the PCI

device, applies an overlay, and then immediately calls of_node_put(dn).

This releases the reference held by the PCI core, potentially freeing

the node if the reference count drops to zero. Later, the same freed

pointer 'dn' is passed to of_platform_default_populate(), leading to a

use-after-free.

The reference to pdev->dev.of_node is owned by the device model and

should not be released by the driver. Remove the erroneous of_node_put()

to prevent premature freeing.