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/corexz.py

@@ -21,8 +21,6 @@ class CoreXZKinematics:
         for s in self.get_steppers():
             s.set_trapq(toolhead.get_trapq())
             toolhead.register_step_generator(s.generate_steps)
-        config.get_printer().register_event_handler("stepper_enable:motor_off",
-                                                    self._motor_off)
         # Setup boundary checks
         max_velocity, max_accel = toolhead.get_max_velocity()
         self.max_z_velocity = config.getfloat(
@@ -63,8 +61,6 @@ class CoreXZKinematics:
                 forcepos[axis] += 1.5 * (position_max - hi.position_endstop)
             # Perform homing
             homing_state.home_rails([rail], forcepos, homepos)
-    def _motor_off(self, print_time):
-        self.clear_homing_state((0, 1, 2))
     def _check_endstops(self, move):
         end_pos = move.end_pos
         for i in (0, 1, 2):