of: unittest: fix possible null-pointer dereferences in of_unittest_property_copy()

of: unittest: fix possible null-pointer dereferences in of_unittest_property_copy()

This function first duplicates p1 and p2 into new, and then checks whether
the duplication succeeds. However, if the duplication fails (e.g.,
kzalloc() returns NULL in __of_prop_dup()), new will be NULL but is still
dereferenced in __of_prop_free(). To ensure that the unit test continues to
run even when duplication fails, add a NULL check before calling
__of_prop_free().

Fixes: 1c5e3d9bf33b ("of: Add a helper to free property struct")
Signed-off-by: Tuo Li <islituo@gmail.com>
Link: https://patch.msgid.link/20260105071438.156186-1-islituo@gmail.com
Signed-off-by: Rob Herring (Arm) <robh@kernel.org>