kernel/kconfig: Disable USB4 PCIe tunneling

The USB4 (TBT) PCIe tunneling functionality triggers a lockdep warning. That is a false-positive according to the TBT maintainer, however there is no patch available to solve the lockdep issue. It does however disable lockdep checks for everything else (and aborts CI runs as the lockdep happens during boot-up).

The above issue only affects machines with a TBT dock connected, however that's an important thing to test, so disable PCIe tunneling until the lockdep issue is solved. This is ok, since iGFX CI doesn't need to test PCIe tunneling.