[arm64] Enable more hardware for RK3399 ChromeOS tablets
Most configs for RK3399 ChromeOS tablets are alreay enabled, as I have been working on a RK3399 Chromebook and got the necessary configs enabled in Debian a long time ago. But I do not have the tablets, so I hadn't considered enabling configs for them at the time.
Enable the remaining hardware for RK3399 ChromeOS tablets as deduced from their device-tree compatibles (rk3399-gru-scarlet-*). Apparently there's only the display panel, camera and Wi-Fi left unenabled.
(I don't have the hardware, but build-tested at least.)