Those comments were either outdated or unneeded here.

I've lost enough hair when this regression surfaced
and almost bothered legion@ but finally saw the

  UUID=...

instead of

  root=UUID=...

in kernel cmdline; this looked as a result of a thinko
that was pretty hard to spot at once but finally
vm/alt-rescue.img works again on Elbrus.

Fixes: 36d25f43