Add 'vendor.' prefix to a vendor HAL service name

To prevent property name collisions between properties of system and
vendor, 'vendor.' prefix must be added to a vendor HAL service name.
You can see the details in http://go/treble-sysprop-compatibility.

Test: succeeded building and tested on a walleye device
Bug: 36796459
Change-Id: I4e8fbee791ec917a8f627a1366f4d44ec7e6febc
diff --git a/light/2.0/default/android.hardware.light@2.0-service.rc b/light/2.0/default/android.hardware.light@2.0-service.rc
index c3284c6..f268706 100644
--- a/light/2.0/default/android.hardware.light@2.0-service.rc
+++ b/light/2.0/default/android.hardware.light@2.0-service.rc
@@ -1,4 +1,4 @@
-service light-hal-2-0 /vendor/bin/hw/android.hardware.light@2.0-service
+service vendor.light-hal-2-0 /vendor/bin/hw/android.hardware.light@2.0-service
     class hal
     user system
-    group system
\ No newline at end of file
+    group system