fixup default machine type and cpu type warning

[il-steffen]

@il-steffen The duplicate aliases are indeed incorrect. The expected behavior would be that the kAFL64 PC type refers to the PIIX machine type. I'll take care of that as soon as possible.

As for the warning, I guess this is actually expected behavior. The kAFL64-Hypervisor-v1 CPU type is used exclusively for PT mode, but when a non-KVM PT kernel is detected, the CPU type is automatically switched to v2 instead and the warning is thrown. We can fix that by simply changing the verbose mode of this warning so that the warning is only shown in debug mode.

Originally posted by @schumilo in #47 (comment)

[il-steffen]

Maybe the warning can be worded to avoid confusion. In my example it was printed even on '-cpu ?'.