emulation and usb_uhci.cc implements the setup for the PIIX3 chipset and the
runtime device change code. The UHCI core is required for the EHCI emulation,
since there can be multiple "companion" controllers for USB 1.1 device handling.
devices like USB disk, cdrom or floppy. Using this feature for the new USB
floppy. Removed static indicators for port activity from the USB HC code.
TODO: Implement status LEDs for USB disk and cdrom.