Fix darkened texture output in GTFO VR

[DSprtn]

In GTFO VR, we use an ancient version of OpenVR/SteamVR and/or the devs prefer to use full float targets, so we end up with an exotic texture input format -DXGI_FORMAT_R16G16B16A16_TYPELESS

If using VRPerfkit, this resulted in a darkened output. If we handle this case too and use the 10/10/10/2 output format, we get results identical to the native output.