The function iommu_domain_alloc returns NULL on platforms without IOMMU
such as msm8974. This resulted in PTR_ERR(-ENODEV) being assigned to
gpu->aspace so the correct code path wasn't taken.
Fixes: ccac7ce373c1 ("drm/msm: Refactor address space initialization") Signed-off-by: Luca Weiss <luca@z3ntu.xyz> Reviewed-by: Jordan Crouse <jcrouse@codeaurora.org> Signed-off-by: Rob Clark <robdclark@chromium.org>