NaN in eye adaptation

What happens is eye adaptation may sample outside view rect, and end up with NaN in eye adaptation buffer, that effectively stays there forever, generating black screen.

Run dyn res on RHI that have a lot of garbage when RT are not initialised like Xbox:

1. +CVars=r.DynamicRes.OperationMode=2
2. +CVars=r.DynamicRes.MinScreenPercentage=66.6666666
3. +CVars=r.DynamicRes.MaxScreenPercentage=100