Revert "fix helix/rev2:edvorakjp build error"

This reverts commit 731dbbe.
Separated into a single PR qmk#16433.

keyboards/helix/rev2/keymaps/edvorakjp/oled.h

@@ -9,4 +9,4 @@ void            render_layer_state(void);
 void            render_logo(void);
 void            render_mode_icon(bool is_windows);
 oled_rotation_t oled_init_user(oled_rotation_t rotation);
-bool            oled_task_user(void);
+void            oled_task_user(void);