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.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

kernel/fail_function.c

@@ -163,10 +163,7 @@ static void fei_debugfs_add_attr(struct fei_attr *attr)
 
 static void fei_debugfs_remove_attr(struct fei_attr *attr)
 {
-	struct dentry *dir;
-
-	dir = debugfs_lookup(attr->kp.symbol_name, fei_debugfs_dir);
-	debugfs_remove_recursive(dir);
+	debugfs_lookup_and_remove(attr->kp.symbol_name, fei_debugfs_dir);
 }
 
 static int fei_kprobe_handler(struct kprobe *kp, struct pt_regs *regs)