kvm tools: Don't use i8042 AUX port

We are enabling i8042 even without VNC or SDL so that we could use it's
reset method to reboot the guest.

AUX port might cause delays during boot. Disable it if the user didn't ask
for VNC or SDL.

Signed-off-by: Sasha Levin <levinsasha928@gmail.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>