Move sensor hal service to class 'hal' from main.

Moving sensor hal service to hal class.

Bug: 36576271
Test: Ensure that sensors still stream.
Change-Id: I1ab984063c48401ee535b9be4df75d554d91578f
(cherry picked from commit 5d0b2e7c373d19eeffc915e5bcb0aaa9187f5a8c)
diff --git a/sensors/1.0/default/android.hardware.sensors@1.0-service.rc b/sensors/1.0/default/android.hardware.sensors@1.0-service.rc
index 50cf787..c085552 100644
--- a/sensors/1.0/default/android.hardware.sensors@1.0-service.rc
+++ b/sensors/1.0/default/android.hardware.sensors@1.0-service.rc
@@ -1,4 +1,4 @@
 service sensors-hal-1-0 /vendor/bin/hw/android.hardware.sensors@1.0-service
-    class main
+    class hal
     user system
     group system