do not issue ioctl from within the io thread

According to Documentation/kvm/api.txt, (and well, to common sense),
we should not be calling vcpu ioctls from within the iothread.
Since vcpu initialization issues a vcpu ioctl, move it a little bit
further in time to prevent it.

Signed-off-by: Glauber Costa <glommer@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
