bltouch: Attempt to verify that the probe raises after each probe attempt

Query the bltouch state during the pin_up command to try and verify
that the probe does actually retract.  This may be useful to detect if
the bltouch enters into an "error" state.

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

klippy/mcu.py

@@ -181,7 +181,8 @@ class MCU_endstop:
                                , self._oid)
     def home_prepare(self):
         pass
-    def home_start(self, print_time, sample_time, sample_count, rest_time):
+    def home_start(self, print_time, sample_time, sample_count, rest_time,
+                   triggered=True):
         clock = self._mcu.print_time_to_clock(print_time)
         rest_ticks = int(rest_time * self._mcu.get_adjusted_freq())
         self._homing = True
@@ -189,7 +190,8 @@ class MCU_endstop:
         self._next_query_print_time = print_time + self.RETRY_QUERY
         self._home_cmd.send(
             [self._oid, clock, self._mcu.seconds_to_clock(sample_time),
-             sample_count, rest_ticks, 1 ^ self._invert], reqclock=clock)
+             sample_count, rest_ticks, triggered ^ self._invert],
+            reqclock=clock)
         for s in self._steppers:
             s.note_homing_start(clock)
     def home_wait(self, home_end_time):