kvm: Dump guest rIP when the guest tried something unsupported

It looks like this in action:

  kvm [5197]: vcpu0, guest rIP: 0xffffffff810187ba unhandled rdmsr: 0xc001102

and helps to pinpoint quickly where in the guest we did the unsupported
thing.

Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>