webos: webos.conf: Release webOS OSE v2.28.0

:Release Notes:
Set software version as webOS OSE v2.28.0.

:Detailed Notes:
Set WEBOS_DISTRO_VERSION_MINOR to "28.0".

:Testing Performed:
Only build tested.

:QA Notes:
No change to image.

:Issues Addressed:
N/A

Cherry-picked-from-commit: fdd1821324b1b976233065fbcdf67e622494edfe
Cherry-picked-from-branch:

builds/webosose/master/'842'

builds/webosose/master/'841'

builds/webosose/master/'840'

builds/webosose/master/'839'

builds/webosose/master/'838'

builds/webosose/master/'837'

builds/webosose/master/'836'

builds/webosose/master/'835'