Remove unused typedef for group children

Author: deshipu

shared-module/displayio/Group.h

@@ -35,10 +35,6 @@
 #include "shared-module/displayio/area.h"
 #include "shared-module/displayio/Palette.h"
 
-typedef struct {
-    mp_obj_t original;
-} displayio_group_child_t;
-
 typedef struct {
     mp_obj_base_t base;
     mp_obj_list_t *members;