cred: add missing return error code when set_cred_ucounts() failed

commit 5e6b8a50 upstream.

If set_cred_ucounts() failed, we need return the error code.

Fixes: 905ae01c

 ("Add a reference to ucounts for each cred")
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Link: https://lkml.kernel.org/r/20210526143805.2549649-1-yangyingliang@huawei.com


Reviewed-by: Alexey Gladkov <legion@kernel.org>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>