device-xiaomi-scorpio: add DRM and flash kernel automatically

This adds DRM modules and GPU firmware to the initramfs, which makes the boot process a little bit more pleasant as the display flickers once and goes up to full brightness early in the process. It also enables automatic kernel flashing.

I've combined both changes them into one commit to avoid incrementing the version/release number twice, but I'm not sure if that's the best approach. They've been split apart now.