Fix broken VMDK and QCOW data image

Got a bit trigger happy with cut'n'paste in the all-in-one patch and
broke the data disk image builds for VMDK and QCOW2.

Also removed the now-obsolete comments from the 1st stage build script.

Change-Id: I817e554e35b015a186e9b8733fe5cca8fc00ee5e