[PATCH] drm/i915/selftests: Fix uninitialized variable

[Chris Wilson]

Quoting Gustavo A. R. Silva (2018-04-24 14:15:45)
> There is a potential execution path in which variable err is
> returned without being properly initialized previously.
> 
> Fix this by initializing variable err to 0.

err is only returned along an error path, returning 0 would not be
useful. Which path? All the error paths look correct to me.
-Chris