Tools/scripts/bump-revision.sh: insert PORTREVISION after DISTVERSIONSUFFIX

When a port has a DISTVERSIONSUFFIX, PORTREVISION was inserted right
after DISTVERSION, before DISTVERSIONSUFFIX, which breaks the variable
order required by portlint. Insert PORTREVISION after the last version
line (DISTVERSIONSUFFIX if present, otherwise DISTVERSION/PORTVERSION).

PR: 259289