[kde-frameworks/plasma] Updated dependencies according to CMakeLists.txt

Building kde-frameworks/plasma failed due to a missing dependency on
kde-frameworks/kdnssd, so I took the chance and synced the ebuild dependencies
against the mandatory dependencies listed in CMakeLists.txt

Package-Manager: portage-2.2.8-r1
[kde-frameworks/kdoctools] Fix app-text/docbook-xml-dtd dep
[sets] Fix kdebase-4.13