[PATCH] drm/i915/selftests: fix check for intel IOMMU

[Chris Wilson]

Quoting Arnd Bergmann (2017-10-05 13:07:22)
> An earlier bugfix tried to work around this build failure:
> 
> drivers/gpu/drm/i915/selftests/mock_gem_device.c: In function 'mock_gem_device':
> drivers/gpu/drm/i915/selftests/mock_gem_device.c:151:20: error: 'struct dev_archdata' has no member named 'iommu'
> 
> Checking for CONFIG_IOMMU_API is not sufficient as a compile-time
> test since that may be enabled in configurations that have neither
> INTEL_IOMMU not AMD_IOMMU enabled. This changes the check to
> INTEL_IOMMU instead, as this is the only case we actually care about.
> 
> Fixes: f46f156ea770 ("drm/i915/selftests: Only touch archdata.iommu when it exists")
> Signed-off-by: Arnd Bergmann <arnd at arndb.de>

I'll take your wisdom. I was lost trying to nail down exactly what
config options we needed to check and settled for something that
appeared good enough (for the small selection of configs I tested).

Reviewed-by: Chris Wilson <chris at chris-wilson.co.uk>
-Chris