drm/tegra: Use DRIVER level for IOMMU aperture message

This allows the message to be shown even if core messages are disabled
globally in DRM.
Signed-off-by: NThierry Reding <treding@nvidia.com>

drivers/gpu/drm/tegra/drm.c

@@ -137,8 +137,8 @@ static int tegra_drm_load(struct drm_device *drm, unsigned long flags)
 		start = geometry->aperture_start;
 		end = geometry->aperture_end;
 
-		DRM_DEBUG("IOMMU context initialized (aperture: %#llx-%#llx)\n",
-			  start, end);
+		DRM_DEBUG_DRIVER("IOMMU aperture initialized (%#llx-%#llx)\n",
+				 start, end);
 		drm_mm_init(&tegra->mm, start, end - start + 1);
 	}