hardware: update missing powerpc entries

Previous patch (4c396c5b7fd7) missed archetypes/release/hardware.adoc
which is used for creating new hardware notes. Update the file to
reflect the patch.

Reviewed by: cperciva
Fixes: 4c396c5b7fd7 ("hardware: Update pSeries entries")
Differential Revision: https://reviews.freebsd.org/D57260