lib/test: use after free in register_test_dev_kmod()

stable inclusion
from stable-v5.10.110
commit 327f07e3704c821ce33e54ef5046bdf69975cb86
bugzilla: https://gitee.com/openeuler/kernel/issues/I574AL

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=327f07e3704c821ce33e54ef5046bdf69975cb86



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[ Upstream commit dc0ce6cc ]

The "test_dev" pointer is freed but then returned to the caller.

Fixes: d9c6a72d ("kmod: add test driver to stress test the module loader")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Yu Liao <liaoyu15@huawei.com>
Reviewed-by: Wei Li <liwei391@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>