Complete ioctl architecture

Add KVM_BIND_DISK command in uapi/linux/kvm.h
Add struct kvm_virtiop_bind_device in uapi/linux/virtioP.h

1. Wait to implement what KVM_BIND_DISK do: specify which guest device trap to distributor.
2. mmap guest's virtqueue with host's virtqueue.
	Do in VIRTIO_MMIO_QUEUE_PFN

When config, distributor reroute to host's mmio directly.
When notify, translate all GPA to PA in virtqueue.
	Do in VIRTIO_MMIO_QUEUE_NOTIFY