kernel/fail_function: fix memory leak with using debugfs_lookup()

kernel/fail_function: fix memory leak with using debugfs_lookup()

When calling debugfs_lookup() the result must have dput() called on it,
otherwise the memory will leak over time.  To make things simpler, just
call debugfs_lookup_and_remove() instead which handles all of the logic
at once.

Cc: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Yang Yingliang <yangyingliang@huawei.com>
Link: https://lore.kernel.org/r/20230202151633.2310897-1-gregkh@linuxfoundation.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>