Clean up ImageReader when VrMode is disabled.

Adjusts some of the startImageReader code as well.

Bug: 34281731
Test: Start a VR App and ensure the virtual display is functional.
Start it a second time and ensure the virtual display is functional.
Previously, any session after the first did not have a functional
virtual display.

Change-Id: Ifbf9fb9466f550ae3e9b30a1d7cf4d2f0a32578b
1 file changed