Prefer passing a USB "pipe" structure over a USB endp encoding.

Prefer passing a USB "pipe" structure over a USB endp encoding.

Instead of passing the "u32 endp" encoding of the usb endpoint,
allocate a "struct usb_pipe" for each end point and pass that.
Allocate a control pipe for every device found.  Support freeing the
pipes after they are done.

Implement pipe allocation and freeing for both UHCI and OHCI
controllers.

Also, don't define every UHCI qh to include a pipe - create a separate
structure "struct uhci_pipe".  Also, be sure to clear the
USBControllers on reset.  Also, convert usb_hub_init to return 0 on
success.  Also, cleanup some of the USB debug messages to make them
more consistent.