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
3 files changed