ad5206: Warn if ad5206 enable pin is inverted

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>

klippy/extras/ad5206.py

@@ -10,6 +10,8 @@ class ad5206:
         printer = config.get_printer()
         enable_pin_params = pins.get_printer_pins(printer).lookup_pin(
             'digital_out', config.get('enable_pin'))
+        if enable_pin_params['invert']:
+            raise pins.error("ad5206 can not invert pin")
         self.mcu = enable_pin_params['chip']
         self.pin = enable_pin_params['pin']
         self.mcu.add_config_object(self)