drm/i915/gtt: Don't leak scratch page on mapping error

Free the scratch page if dma mapping fails.
Signed-off-by: NMika Kuoppala <mika.kuoppala@intel.com>
Reviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_gem_gtt.c

@@ -2143,8 +2143,10 @@ static int setup_scratch_page(struct drm_device *dev)
 #ifdef CONFIG_INTEL_IOMMU
 	dma_addr = pci_map_page(dev->pdev, page, 0, PAGE_SIZE,
 				PCI_DMA_BIDIRECTIONAL);
-	if (pci_dma_mapping_error(dev->pdev, dma_addr))
+	if (pci_dma_mapping_error(dev->pdev, dma_addr)) {
+		__free_page(page);
 		return -EINVAL;
+	}
 #else
 	dma_addr = page_to_phys(page);
 #endif