stepper_enable: Move motor_off() logic to stepper_enable.py

Directly disable all the stepper motors on a global motor_off() from
the StepperEnable() class in stepper_enable.py.  This simplifies the
toolhead and kinematic classes.

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

klippy/kinematics/corexy.py

@@ -20,6 +20,8 @@ class CoreXYKinematics:
         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(
@@ -63,10 +65,8 @@ class CoreXYKinematics:
                 forcepos[axis] += 1.5 * (position_max - hi.position_endstop)
             # Perform homing
             homing_state.home_rails([rail], forcepos, homepos)
-    def motor_off(self, print_time):
+    def _motor_off(self, print_time):
         self.limits = [(1.0, -1.0)] * 3
-        for rail in self.rails:
-            rail.motor_enable(print_time, 0)
     def _check_endstops(self, move):
         end_pos = move.end_pos
         for i in (0, 1, 2):