Earlier in the 2.5 development cycle a patch was applied that changed
the reference counting behaviour for USB devices.

There are a couple of problems with the change:
- It made the USB code more complicated as a whole with the introduction
  of an additional cleanup path for devices. Using the traditional method
  of reference counting, cleanup is handled implictly
- It reduces functionality by requiring a callback for all references to
  the device, but doesn't provide a method of providing callbacks for
  references. It relies on the hardcoded device driver ->disconnect and
  HCD ->deallocate method for callbacks

The traditional method of using reference counting supports as many
reference users as needed, without complicating it with mandatory
callbacks to cleanup references.

The change in 2.5 also only helps catch one subset of programming
problem in device drivers, the case where it decrements too many times.
That is of dubious debugging value.

So, this patch reverts the change and makes the reference counting
behave like it does in the rest of the kernel as well as how the USB
code does in 2.4.

This patch doesn't remove all of the superfluous code. Some drivers,
like usb-ohci, ohci-hcd and ehci-hcd have some code that is no longer
needed. I wanted to spend some more time with those drivers since the
changes weren't as trivial as uhci.c and usb-uhci.c.

I've tested with uhci and usb-ohci with no adverse effects.