simplify some unnecessary complex code

getSensorType() ran in O(n) instead of O(1). fix that.

Change-Id: Idcf29e46fc34db32604a0d8e5a9156486783b74f
diff --git a/include/android/sensor.h b/include/android/sensor.h
index f163f18..4683298 100644
--- a/include/android/sensor.h
+++ b/include/android/sensor.h
@@ -122,6 +122,7 @@
         float           distance;
         float           light;
         float           pressure;
+        float           step_counter;
     };
     int32_t reserved1[4];
 } ASensorEvent;