[patch] drm/nouveau/platform: checking for IS_ERR() instead of NULL

[Alexandre Courbot]

On 04/21/2015 06:25 PM, Dan Carpenter wrote:
> iommu_domain_alloc() returns NULL on error, it doesn't return error
> pointers.

Oops, that's right.

Reviewed-by: Alexandre Courbot <acourbot at nvidia.com>