drm/core: clean up references to drm_dev_unref()

This is a continuation of a previous commit ("drm: introduce drm_dev_{get/put}
functions") to replace all references to drm_dev_unref() in drm core files with
drm_dev_put().

Signed-off-by: Aishwarya Pant <aishpant@gmail.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20170926170400.GA7671@aishwarya
diff --git a/drivers/gpu/drm/drm_pci.c b/drivers/gpu/drm/drm_pci.c
index 1235c98..4db9c51 100644
--- a/drivers/gpu/drm/drm_pci.c
+++ b/drivers/gpu/drm/drm_pci.c
@@ -274,7 +274,7 @@ int drm_get_pci_dev(struct pci_dev *pdev, const struct pci_device_id *ent,
 	drm_pci_agp_destroy(dev);
 	pci_disable_device(pdev);
 err_free:
-	drm_dev_unref(dev);
+	drm_dev_put(dev);
 	return ret;
 }
 EXPORT_SYMBOL(drm_get_pci_dev);