Core: Update libusb.h header in accordance with the latest USB specs

Core: Update libusb.h header in accordance with the latest USB specs

* IMPORTANT: This update fixes a typo in the API where MaxPower was being
  used instead of bMaxPower, with the latter being what is actually in
  the specs.
* As a result, applications that were using MaxPower need to be updated
  for bMaxPower.
* If you must maintain compatibility with libusb or older versions of
  libusbx, you may also want to either use a #define or copy/paste
  struct libusb_config_descriptor from libusb.h under a new name, and
  then use a cast on calls that require it. For more info, see the
  1.0.13 release notes in the NEWS file.
* Also update copyright notice