Fix the device ID struct to reflect the actual structure used by IOS.
It turns out that offset 2 is the internal device index. The reason
that field seemed to be "0x1e - interface_number" is that IOS only
keeps track of 32 devices and always looks for free entries from
the end of the internal array. With each USB interface being exposed
as a separate USBv5 device, "0x1e - interface_number" was mostly
correct... but wrong!
We also made the assumption that the interface number can be
identified from just a USBV5 device ID, which is definitely not true.
VEN (and HID) keep track of the interface number in the internal struct
instead of "reconstructing" it from the device ID (which is normally
not possible if we were generating IDs correctly)
This commit fixes all of these inaccuracies.