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

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.

Fixes: 26409dd04589 ("of: unittest: Add pci_dt_testdrv pci driver")
Cc: stable@vger.kernel.org
Signed-off-by: Wentao Liang <vulab@iscas.ac.cn>
Link: https://patch.msgid.link/20260409034859.429071-1-vulab@iscas.ac.cn
Signed-off-by: Rob Herring (Arm) <robh@kernel.org>