Make use of /usr/sbin/ebslvm

The new baseami provides /usr/sbin/ebslvm which we use
here to mount ebs volumes in an lvm in /mnt, that means
we no longer provide the symlink during the build phase
ahh, I better understand now. Thanks, and I agree. We're not in the habit of ssh'ing onto our boxes (nor should we be!) so wasn't thinking of it from that context.