[gta02-core] USB schematics

[Rene Harder]

Hi

I finished the USB part and commited to svn.

I found some problems while i was working the schematics.

The reference of some varistors start with C instead of D.
Maybe there supposed to be capacitors, which actually would make sense.
There are 3 varistors on the USB_VBUS line 2 of them labeled with C.
Anyone an idea, why there are 3, I think one would be more than enough.

There is an error in the om schematics, the varistors connected to the
USB power line have an allowed dc operating voltage of 5.6V (data sheet)
instead of 2.4V (om schematics).

Also om is using capitalized SI prefixes e.g. kilo=K, nano=N. That might
cause confusion if you have milli=M and Mega=M. I think it's better to
stay with the official captions  kilo=k, nano=n, mega=M etc.