Define the ISensorsCallback

The ISensorsCallback will be used to push notifications into the
sensors framework, such as when dynamic sensors are connected.

Bug: 111070257
Test: Compiles
Change-Id: I681e6de341a80016983a3ab7fa45284ee9104918
diff --git a/sensors/2.0/Android.bp b/sensors/2.0/Android.bp
index f614834..3b948a9 100644
--- a/sensors/2.0/Android.bp
+++ b/sensors/2.0/Android.bp
@@ -9,6 +9,7 @@
     srcs: [
         "types.hal",
         "ISensors.hal",
+        "ISensorsCallback.hal",
     ],
     interfaces: [
         "android.hardware.sensors@1.0",