Possible Mac build fix.

The error was this:

  system/core/adb/usb_osx.cpp:203:74: error: values of type 'UInt32' should not
  be used as format arguments; add an explicit cast to 'unsigned int' instead
  [-Werror,-Wformat]
    snprintf(devpathBuf, sizeof(devpathBuf), "usb:%" PRIu32 "X", locationId);
                                                  ~~~            ^~~~~~~~~~
                                                                 (unsigned int)

Which seems to be because on LP64 UInt32 is "unsigned int" but on LP32 it was
"unsigned long". We don't have to care about LP32, so -- if we can -- we're
probably better off just using uint32_t instead of UInt32.

Change-Id: I576f76cf2016ee59caccbc317ef74b6e8d71d722