simplify motion config dirty state

Author: dirixmjm

plugwise_usb/api.py

@@ -233,12 +233,14 @@ class MotionConfig:
         reset_timer: int | None: Motion reset timer in minutes before the motion detection is switched off.
         daylight_mode: bool | None: Motion detection when light level is below threshold.
         sensitivity_level: MotionSensitivity | None: Motion sensitivity level.
+        dirty: bool: Settings changed, device update pending
 
     """
 
     daylight_mode: bool | None = None
     reset_timer: int | None = None
     sensitivity_level: MotionSensitivity | None = None
+    dirty: bool = False
 
 
 @dataclass