revert attempts to make struct private

feat/priate-struct was create as snapshot before this commit

src/extra/widgets/keyboard/lv_keyboard.h

@@ -49,10 +49,7 @@ typedef struct {
     lv_btnmatrix_t btnm;
     lv_obj_t * ta;              /*Pointer to the assigned text area*/
     lv_keyboard_mode_t mode;    /*Key map type*/
-} _lv_keyboard_t;
-
-/*Trick to no expose the fields of the struct in the MicroPython binding*/
-typedef _lv_keyboard_t lv_keyboard_t;
+} lv_keyboard_t;
 
 extern const lv_obj_class_t lv_keyboard_class;