force_move: Use strings for axes to clear in clear_homing_state()

Pass a string such as "xyz" to kin.clear_homing_state().  This makes
the parameter a little less cryptic.

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

klippy/kinematics/delta.py

@@ -103,9 +103,9 @@ class DeltaKinematics:
         self.limit_xy2 = -1.
         if homing_axes == "xyz":
             self.need_home = False
-    def clear_homing_state(self, axes):
+    def clear_homing_state(self, clear_axes):
         # Clearing homing state for each axis individually is not implemented
-        if 0 in axes or 1 in axes or 2 in axes:
+        if clear_axes:
             self.limit_xy2 = -1
             self.need_home = True
     def home(self, homing_state):