KVM: use after free in kvm_ioctl_create_device()

We should move the ops->destroy(dev) after the list_del(&dev->vm_node)
so that we don't use "dev" after freeing it.

Fixes: a28ebea2adc4 ("KVM: Protect device ops->create and list_add with kvm->lock")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
static inline int check_user_page_hwpoison(unsigned long addr)
{
	int rc, flags = FOLL_HWPOISON | FOLL_WRITE;

	rc = get_user_pages(addr, 1, flags, NULL, NULL);
	return rc == -EHWPOISON;
}

static inline int check_user_page_hwpoison(unsigned long addr)
{
	int rc, flags = FOLL_HWPOISON | FOLL_WRITE;

	rc = get_user_pages(addr, 1, flags, NULL, NULL);
	return rc == -EHWPOISON;
}
