D20225: use more appropriate plasma-specific icon for plasma category

[Aleix Pol Gonzalez]

apol accepted this revision.
This revision is now accepted and ready to land.

REPOSITORY
  R252 Framework Integration

BRANCH
  master

REVISION DETAIL
  https://phabricator.kde.org/D20225

To: sitter, apol
Cc: kde-frameworks-devel, michaelh, ngraham, bruns