clients/eventdemo: Remove duplicated param entries

Removes doxygen warning.

Fixes #664

Signed-off-by: Marius Vlad <marius.vlad@collabora.com>

clients/eventdemo.c

@@ -351,8 +351,6 @@ axis_discrete_handler(struct widget *widget, struct input *input,
  * \param widget widget
  * \param input input device that caused the motion event
  * \param time time the event happened
- * \param x absolute x position
- * \param y absolute y position
  * \param x x position relative to the window
  * \param y y position relative to the window
  * \param data user data associated to the window