[usb] USB Core Update

[Rudolf Usselmann <rudi@asics.ws>]

New release of the code is checked in !

Some of the changes are:
- Moved Buffer Memory (SSRAM) outside the core
- Added Core Configuration
- Modified DMA Operations
- Added OTS_STOP bit in endpoint CSR register
- Added łOUT is smaller than MAX_PL_SZ˛ interrupt
- Fixed addresses of registers
- Many other small fixes and additions


I also updated the Spec. The new version (1.2) can be found here:
http://www.opencores.org/cores/usb/usb_doc.pdf

Web page was also updated, to reflect all the changes ...

Phu, I need a beer now,
Cheers !
-- 
rudi