fail_function: fix wrong use of fei_attr_remove()

If register_kprobe() fails, the new attr is not added to the list yet, so
it should call fei_attr_free() intstead.

Link: https://lkml.kernel.org/r/20220826073337.2085798-3-yangyingliang@huawei.com


Fixes: 4b1a29a7 ("error-injection: Support fault injection framework")
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>