of: unittest: fix null pointer dereferencing in of_unittest_find_node_by_name()

of: unittest: fix null pointer dereferencing in of_unittest_find_node_by_name()

[ Upstream commit d6ce4f0ea19c32f10867ed93d8386924326ab474 ]

when kmalloc() fail to allocate memory in kasprintf(), name
or full_name will be NULL, strcmp() will cause
null pointer dereference.

Fixes: 0d638a07d3a1 ("of: Convert to using %pOF instead of full_name")
Signed-off-by: Ruan Jinjie <ruanjinjie@huawei.com>
Link: https://lore.kernel.org/r/20230727080246.519539-1-ruanjinjie@huawei.com
Signed-off-by: Rob Herring <robh@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>