vdpa: Remove unused declarations

There is no caller and implementation in tree.

Signed-off-by: Yue Haibing <yuehaibing@huawei.com>
Message-Id: <20240819140930.122019-1-yuehaibing@huawei.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Shannon Nelson <shannon.nelson@amd.com>
Reviewed-by: Zhu Lingshan <lingshan.zhu@kernel.org>
Reviewed-by: Shannon Nelson &amp;lt;&lt;a href="mailto:shannon.nelson@amd.com" <target="_blank"&gt;shannon.nelson@amd.com&lt;/a&gt;&amp;gt;&lt;br>
Reviewed-by: Zhu Lingshan <lingshan.zhu@kernel.org>