use better strings for dri devices

Summary:
the Accelerator grouping entry avoided plural mutation for 5.18.

Test Plan: hoping for the best!

Reviewers: ngraham

Reviewed By: ngraham

Subscribers: ngraham, plasma-devel

Tags: #plasma

Differential Revision: https://phabricator.kde.org/D27982

# Conflicts:
#	Modules/opengl/opengl.cpp