Add missing [privsep_entrypoint]/helper_command

Closes-Bug: ATMOSPHERE-648
Change-Id: I12243527ad763bb249195220093717d68de050f6
diff --git a/images/nova/Dockerfile b/images/nova/Dockerfile
index 40a5210..bc8a6d2 100644
--- a/images/nova/Dockerfile
+++ b/images/nova/Dockerfile
@@ -29,7 +29,7 @@
 RUN <<EOF bash -xe
 apt-get update -qq
 apt-get install -qq -y --no-install-recommends \
-    ceph-common genisoimage iproute2 libosinfo-bin lsscsi ndctl nfs-common nvme-cli openssh-client ovmf python3-libvirt python3-rados python3-rbd qemu-efi-aarch64 qemu-block-extra qemu-utils sysfsutils udev util-linux swtpm swtpm-tools libtpms0
+    ceph-common dmidecode genisoimage iproute2 libosinfo-bin lsscsi ndctl nfs-common nvme-cli openssh-client ovmf python3-libvirt python3-rados python3-rbd qemu-efi-aarch64 qemu-block-extra qemu-utils sysfsutils udev util-linux swtpm swtpm-tools libtpms0
 apt-get clean
 rm -rf /var/lib/apt/lists/*
 EOF