ioapic: fix error report value of def version

It should be 0x20, rather than 0x11.

Signed-off-by: Peter Xu <peterx@redhat.com>
Message-Id: <1486106298-3699-3-git-send-email-peterx@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>