drm/vmwgfx/vmwgfx_drv: Fix an error path in vmw_setup_pci_resources()

The devm_memremap() function never returns NULL, it returns error
pointers so the test needs to be fixed.  Also we need to call
pci_release_regions() to avoid a memory leak.

Fixes: be4f77a ("drm/vmwgfx: Cleanup fifo mmio handling")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Zack Rusin <zackr@vmware.com>
Link: https://patchwork.freedesktop.org/patch/msgid/YA6FMboLhnE3uSvb@mwanda
(cherry picked from commit f3ebd4e)
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>

drivers/gpu/drm/vmwgfx/vmwgfx_drv.c

@@ -668,9 +668,10 @@ static int vmw_setup_pci_resources(struct vmw_private *dev,
 				      fifo_size,
 				      MEMREMAP_WB);
 
-	if (unlikely(dev->fifo_mem == NULL)) {
+	if (IS_ERR(dev->fifo_mem)) {
 		DRM_ERROR("Failed mapping FIFO memory.\n");
-		return -ENOMEM;
+		pci_release_regions(pdev);
+		return PTR_ERR(dev->fifo_mem);
 	}
 
 	/*