platform/x86: think-lmi: Use kfree_sensitive instead of kfree

key might contain private part of the key, so better use
kfree_sensitive to free it.
Signed-off-by: Wang Ming <machel@vivo.com>
Link: https://lore.kernel.org/r/20230717101114.18966-1-machel@vivo.comReviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>

drivers/platform/x86/think-lmi.c

@@ -719,12 +719,12 @@ static ssize_t cert_to_password_store(struct kobject *kobj,
 	/* Format: 'Password,Signature' */
 	auth_str = kasprintf(GFP_KERNEL, "%s,%s", passwd, setting->signature);
 	if (!auth_str) {
-		kfree(passwd);
+		kfree_sensitive(passwd);
 		return -ENOMEM;
 	}
 	ret = tlmi_simple_call(LENOVO_CERT_TO_PASSWORD_GUID, auth_str);
 	kfree(auth_str);
-	kfree(passwd);
+	kfree_sensitive(passwd);
 
 	return ret ?: count;
 }