Adaption of LCD info screen

Here comes a compile-time operation to match the extruder symbols on the
info screen to the set number of extruders in configuration.h.
When only one extruder is selected, the "1" on the symbol will not be
displayed.

Marlin/dogm_lcd_implementation.h

@@ -245,9 +245,6 @@ static void lcd_implementation_status_screen()
 		 u8g.drawBox(38,17,2,2);
 		 u8g.setColorIndex(1);	// black on white
 		}
- #else
- u8g.setPrintPos(31,27);
- u8g.print("---");
  #endif
  
  // Extruder 3
@@ -266,9 +263,6 @@ static void lcd_implementation_status_screen()
 		 u8g.drawBox(62,17,2,2);
 		 u8g.setColorIndex(1);	// black on white
 		}
- #else
- u8g.setPrintPos(55,27);
- u8g.print("---");
  #endif
  
  // Heatbed