stepper_enable: Directly call clear_homing_state() on motor off event

Call clear_homing_state() on each motor off event.  This simplifies
the kinematic classes as they no longer need to register and handle
the motor_off event.

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

klippy/kinematics/delta.py

@@ -23,8 +23,6 @@ class DeltaKinematics:
             stepper_configs[2], need_position_minmax = False,
             default_position_endstop=a_endstop)
         self.rails = [rail_a, rail_b, rail_c]
-        config.get_printer().register_event_handler("stepper_enable:motor_off",
-                                                    self._motor_off)
         # Setup max velocity
         self.max_velocity, self.max_accel = toolhead.get_max_velocity()
         self.max_z_velocity = config.getfloat(
@@ -116,8 +114,6 @@ class DeltaKinematics:
         forcepos = list(self.home_position)
         forcepos[2] = -1.5 * math.sqrt(max(self.arm2)-self.max_xy2)
         homing_state.home_rails(self.rails, forcepos, self.home_position)
-    def _motor_off(self, print_time):
-        self.clear_homing_state((0, 1, 2))
     def check_move(self, move):
         end_pos = move.end_pos
         end_xy2 = end_pos[0]**2 + end_pos[1]**2