qemu: Add an ID to the qemu storage
While trying to test all possible qemu machine on LAVA, I found that most cannot ran tests since they are stored on a qcow2 image. This qcow2 image is then connected by any of IDE, SCSI, virtio via this qemu option "-drive format=qcow2,file=/var/lib/lava/dispatcher/tmp/jobid/apply-overlay-guest-49d_bpy5/lava-guest.qcow2,media=disk,if=XXXX"
But for some QEMU machine all thoses bus are not availlable. For example the qemu ARM cubieboard does not have any of thoses. After some research and discussion on #qemu, the only way to add the LAVA qemu test storage on cubieboard is with: "-device ide-hd,drive=lavatest" where drive=id must be the same as the id present on "-drive"
So this patch adds such id on "-drive" option