[oe] packaged staging issue; additional packages

[Frans Meulenbroeks]

Found it; fixed it; tested it; pushed it;

Root case was that packaged-staging.bbclass was not updated when
DISTRO_PR was introduced.
This caused the generation of pathnames which were missing the
DISTRO_PR part. Fixed it by adding + "${DISTRO_PR}" to the places
involved.

Kudos to RP for pointing me to the proper direction.

FM