commented out functions without definition

Functions that are declared but not defined will cause the micropython build to fail, since it would assume, from file header, that these functions are available and will try to call them (linker error)

src/lv_core/lv_refr.h

@@ -63,14 +63,14 @@ void lv_inv_area(lv_disp_t * disp, const lv_area_t * area_p);
 /**
  * Get the number of areas in the buffer
  * @return number of invalid areas
- */
 uint16_t lv_refr_get_buf_size(void);
+ */
 
 /**
  * Pop (delete) the last 'num' invalidated areas from the buffer
  * @param num number of areas to delete
- */
 void lv_refr_pop_from_buf(uint16_t num);
+ */
 
 /**
  * Get the display which is being refreshed

src/lv_objx/lv_spinbox.h

@@ -126,8 +126,8 @@ void lv_spinbox_set_range(lv_obj_t * spinbox, int32_t range_min, int32_t range_m
  * Set spinbox callback on calue change
  * @param spinbox pointer to spinbox
  * @param cb Callback function called on value change event
- */
 void lv_spinbox_set_value_changed_cb(lv_obj_t * spinbox, lv_spinbox_value_changed_cb_t cb);
+ */
 
 /**
  * Set spinbox left padding in digits count (added between sign and first digit)