drm/ati_pcigart: Fix error code in drm_ati_pcigart_init()

The drm_ati_pcigart_init() function was originally suppose to return one
on success and zero on failure, but these days it returns a mix of
zero, one and -ENOMEM on failure.

This patch cleans it up and modifies the caller so now the function
returns zero on success and negative error codes on failure.

Signed-off-by: Dan Carpenter <[e-mail]>
Signed-off-by: Daniel Vetter <[e-mail]>
Link: https://patchwork.freedesktop.org/patch/msgid/20181217070344.GC12159@kadam

drivers/gpu/drm/ati_pcigart.c

···
 	unsigned long pages;
 	u32 *pci_gart = NULL, page_base, gart_idx;
 	dma_addr_t bus_address = 0;
-	int i, j, ret = 0;
+	int i, j, ret = -ENOMEM;
 	int max_ati_pages, max_real_pages;
 
 	if (!entry) {
···
 		if (pci_set_dma_mask(dev->pdev, gart_info->table_mask)) {
 			DRM_ERROR("fail to set dma mask to 0x%Lx\n",
 				  (unsigned long long)gart_info->table_mask);
-			ret = 1;
+			ret = -EFAULT;
 			goto done;
 		}
 
···
 			drm_ati_pcigart_cleanup(dev, gart_info);
 			address = NULL;
 			bus_address = 0;
+			ret = -ENOMEM;
 			goto done;
 		}
 		page_base = (u32) entry->busaddr[i];
···
 			page_base += ATI_PCIGART_PAGE_SIZE;
 		}
 	}
-	ret = 1;
+	ret = 0;
 
 #if defined(__i386__) || defined(__x86_64__)
 	wbinvd();

drivers/gpu/drm/r128/r128_cce.c

···
 		dev_priv->gart_info.addr = NULL;
 		dev_priv->gart_info.bus_addr = 0;
 		dev_priv->gart_info.gart_reg_if = DRM_ATI_GART_PCI;
-		if (!drm_ati_pcigart_init(dev, &dev_priv->gart_info)) {
+		rc = drm_ati_pcigart_init(dev, &dev_priv->gart_info);
+		if (rc) {
 			DRM_ERROR("failed to init PCI GART!\n");
 			dev->dev_private = (void *)dev_priv;
 			r128_do_cleanup_cce(dev);
-			return -ENOMEM;
+			return rc;
 		}
 		R128_WRITE(R128_PCI_GART_PAGE, dev_priv->gart_info.bus_addr);
 #if IS_ENABLED(CONFIG_AGP)