Remove bold formatting of device name

Summary: D27543 set the label to plaintext, for a reason I assume, but the device name label actually uses style tags. We either need to drop that or reenable rich text formatting

Test Plan: No longer see <b>device name</b>

Reviewers: Plasma, drosca, davidedmundson

Reviewed By: drosca

Subscribers: ngraham, broulik, pino, plasma-devel

Tags: Plasma

Differential Revision: https://phabricator.kde.org/D27574