Follow up fixes to various PRs. (#13334)

- Ensure `MarlinUI:get_progress` is defined for `ExtUI`.
- Fix for `BACKLASH_SMOOTHING` with small segments.
  `BACKLASH_SMOOTHING` with extremely small segments failed to fully correct due to the correction factor being rounded down. Rounding up ensures the entire backlash will converge to zero even for small segments.
- Add pinout for the beta revision `EINSY_RETRO`.
- Update soft endstops with tool offsets (for toolchange et. al. move clamping) (#12568)

Marlin/src/lcd/ultralcd.cpp

@@ -397,20 +397,6 @@ bool MarlinUI::get_blink() {
   #endif
 #endif
 
-#if HAS_PRINT_PROGRESS
-  uint8_t MarlinUI::get_progress() {
-    #if ENABLED(LCD_SET_PROGRESS_MANUALLY)
-      uint8_t &progress = progress_bar_percent;
-    #else
-      uint8_t progress = 0;
-    #endif
-    #if ENABLED(SDSUPPORT)
-      if (IS_SD_PRINTING()) progress = card.percentDone();
-    #endif
-    return progress;
-  }
-#endif
-
 void MarlinUI::status_screen() {
 
   #if HAS_LCD_MENU
@@ -1321,4 +1307,18 @@ void MarlinUI::update() {
     set_status_P(msg, -1);
   }
 
+  #if HAS_PRINT_PROGRESS
+    uint8_t MarlinUI::get_progress() {
+      #if ENABLED(LCD_SET_PROGRESS_MANUALLY)
+        uint8_t &progress = progress_bar_percent;
+      #else
+        uint8_t progress = 0;
+      #endif
+      #if ENABLED(SDSUPPORT)
+        if (IS_SD_PRINTING()) progress = card.percentDone();
+      #endif
+      return progress;
+    }
+  #endif
+
 #endif // HAS_SPI_LCD || EXTENSIBLE_UI