qemu: hotplug: Adjust error path for attach scsi disk
qemu: hotplug: Adjust error path for attach scsi disk

Adjust error path logic to make it clearer how to undo the failed add.

Signed-off-by: John Ferlan <87558058f6f829e5ec976c8ef960720af4ff9c7d@redhat.com>

eskultety/libvirt,andreabolognani/libvirt,taget/libvirt,andreabolognani/libvirt,VenkatDatta/libvirt,crobinso/libvirt,andreabolognani/libvirt,libvirt/libvirt,fabianfreyer/libvirt,VenkatDatta/libvirt,jfehlig/libvirt,jardasgit/libvirt,nertpinx/libvirt,taget/libvirt,nertpinx/libvirt,libvirt/libvirt,jardasgit/libvirt,taget/libvirt,olafhering/libvirt,VenkatDatta/libvirt,datto/libvirt,crobinso/libvirt,datto/libvirt,zippy2/libvirt,andreabolognani/libvirt,olafhering/libvirt,andreabolognani/libvirt,taget/libvirt,eskultety/libvirt,eskultety/libvirt,jardasgit/libvirt,nertpinx/libvirt,taget/libvirt,olafhering/libvirt,jfehlig/libvirt,datto/libvirt,libvirt/libvirt,crobinso/libvirt,jardasgit/libvirt,datto/libvirt,jfehlig/libvirt,nertpinx/libvirt,VenkatDatta/libvirt,fabianfreyer/libvirt,fabianfreyer/libvirt,olafhering/libvirt,eskultety/libvirt,fabianfreyer/libvirt,VenkatDatta/libvirt,jfehlig/libvirt,jardasgit/libvirt,zippy2/libvirt,nertpinx/libvirt,zippy2/libvirt,eskultety/libvirt,fabianfreyer/libvirt,libvirt/libvirt,crobinso/libvirt,datto/libvirt,zippy2/libvirt