- Move tunable defines into usb_core.h and dependancy towards usb_defs.h
- Leave hardcoded defines in "usb_defs.h".
- Allow overriding all tunable defines.
- Add more customisable typedefs.
- Correct maximum device number.
Submitted by: Hans Petter Selasky
Improvements to "usb2_transfer_setup()" and "usb2_transfer_unsetup()". Set
"ppxfer[n]" when the transfer setup is complete to prevent races. Remove
redundant NULL-checks from "usb2_transfer_unsetup()".
Submitted by: Hans Petter Selasky