drivers: bma421: Switch over to reset_step_counter()

Currently the bma421 driver simple re-initializes the sensor when asked
to set the step counter to zero. Switch over to the proper function
for this.

Signed-off-by: Daniel Thompson <daniel@redfelineninja.org.uk>

wasp/drivers/bma421.py

@@ -48,6 +48,4 @@ class BMA421:
     def steps(self, value):
         if value != 0:
             raise ValueError()
-        # TODO: There is a more efficient way to reset the step counter
-        #       but I haven't looked it up yet!
-        self.reset()
+        self._dev.reset_step_counter()