endstop_phase: Fix endstop_phase on trinamic drivers that aren't inverted

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

klippy/mcu.py

@@ -70,6 +70,8 @@ class MCU_stepper:
         return self._oid
     def get_step_dist(self):
         return self._step_dist
+    def is_dir_inverted(self):
+        return self._invert_dir
     def calc_position_from_coord(self, coord):
         return self._ffi_lib.itersolve_calc_position_from_coord(
             self._stepper_kinematics, coord[0], coord[1], coord[2])