KVM: Clean up coalesced_mmio destruction

We invoke kfree() on a data member instead of the structure.  This works today
because the kvm_io_device is the first element of the private structure, but
this could change in the future, so lets clean this up.

Signed-off-by: Gregory Haskins <ghaskins@novell.com>
Acked-by: Chris Wright <chrisw@sous-sol.org>
Signed-off-by: Avi Kivity <avi@redhat.com>

virt/kvm/coalesced_mmio.c

@@ -80,7 +80,10 @@ static void coalesced_mmio_write(struct kvm_io_device *this,
 
 static void coalesced_mmio_destructor(struct kvm_io_device *this)
 {
-	kfree(this);
+	struct kvm_coalesced_mmio_dev *dev =
+		(struct kvm_coalesced_mmio_dev *)this->private;
+
+	kfree(dev);
 }
 
 int kvm_coalesced_mmio_init(struct kvm *kvm)