Fix mouse settings not being loaded when a mouse is connected

Keyboard daemon was calling into the wrong module name. There are only
so much kcminit modules, and all of them are required to be named and
referenced with a "kcm_" prefix.

Postmortem:

- Mouse settings' saving and loading worked fine.
- Changing settings on the fly worked fine, and if they were not loaded
  before due to this bug, KCM loaded them and applied, after which
  mouse worked fine until disconnected.
- Starting computer with mouse already connected worked fine.
- Plug&Play (i.e. connecting mouse after session has started) was the
  only thing that was broken, because this reconfiguration failed to
  launch the proper mouse module.

Co-Authored-By: David Edmundson <kde@davidedmundson.co.uk>
BUG: 435113
FIXED-IN: 5.24.7, 5.25.4, 5.26
(cherry picked from commit 0d7eccfb)