VR: Rename HIDL service name from vr_hwcomposer to vr

This is part of an effort to simplify service names.

Bug: 36564122
Test: Ran on device and verified SurfaceFlinger connects to vr_wm
Change-Id: I3e2a2b778f3f0d2066bf5b756263de4b238b2f83
diff --git a/services/surfaceflinger/DisplayHardware/ComposerHal.cpp b/services/surfaceflinger/DisplayHardware/ComposerHal.cpp
index c6e6dcb..d9bddb5 100644
--- a/services/surfaceflinger/DisplayHardware/ComposerHal.cpp
+++ b/services/surfaceflinger/DisplayHardware/ComposerHal.cpp
@@ -129,7 +129,7 @@
       mIsUsingVrComposer(useVrComposer)
 {
     if (mIsUsingVrComposer) {
-        mComposer = IComposer::getService("vr_hwcomposer");
+        mComposer = IComposer::getService("vr");
     } else {
         mComposer = IComposer::getService(); // use default name
     }