deploy: Start hardlinking kernel/initramfs on single-part again
deploy: Start hardlinking kernel/initramfs on single-part again

Commit
https://github.com/ostreedev/ostree/commit/1810de2b51680dbf35fdbd33d0a8d7e65eadc91f
lost an optimization where we would try hardlinks for the
kernel/initramfs in `/boot`.  This would be a noticeable space savings
on single-partition systems.

Closes: #277
Approved by: gatispaeglis

GNOME/ostree,gatispaeglis/ostree,gatispaeglis/ostree,gatispaeglis/ostree,gatispaeglis/ostree,GNOME/ostree,GNOME/ostree,GNOME/ostree,gatispaeglis/ostree,gatispaeglis/ostree,GNOME/ostree