drm/mgag200: Use pcim_enable_device()

Using the managed function simplifies the error handling. After
unloading the driver, the PCI device should now get disabled as
well.
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20200605135803.19811-4-tzimmermann@suse.de

drivers/gpu/drm/mgag200/mgag200_drv.c

@@ -52,15 +52,13 @@ static int mga_pci_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
 
 	drm_fb_helper_remove_conflicting_pci_framebuffers(pdev, "mgag200drmfb");
 
-	ret = pci_enable_device(pdev);
+	ret = pcim_enable_device(pdev);
 	if (ret)
 		return ret;
 
 	dev = drm_dev_alloc(&driver, &pdev->dev);
-	if (IS_ERR(dev)) {
-		ret = PTR_ERR(dev);
-		goto err_pci_disable_device;
-	}
+	if (IS_ERR(dev))
+		return PTR_ERR(dev);
 
 	dev->pdev = pdev;
 	pci_set_drvdata(pdev, dev);
@@ -81,8 +79,6 @@ static int mga_pci_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
 	mgag200_driver_unload(dev);
 err_drm_dev_put:
 	drm_dev_put(dev);
-err_pci_disable_device:
-	pci_disable_device(pdev);
 	return ret;
 }