drm/vc4: Replace drm_dev_unref with drm_dev_put

This patch unifies the naming of DRM functions for reference counting
of struct drm_device. The resulting code is more aligned with the rest
of the Linux kernel interfaces.
Signed-off-by: NThomas Zimmermann <tzimmermann@suse.de>
Signed-off-by: NEric Anholt <eric@anholt.net>
Link: https://patchwork.freedesktop.org/patch/msgid/20180717085428.18500-1-tzimmermann@suse.de

drivers/gpu/drm/vc4/vc4_drv.c

@@ -288,7 +288,7 @@ static int vc4_drm_bind(struct device *dev)
 
 	ret = vc4_bo_cache_init(drm);
 	if (ret)
-		goto dev_unref;
+		goto dev_put;
 
 	drm_mode_config_init(drm);
 
@@ -313,8 +313,8 @@ static int vc4_drm_bind(struct device *dev)
 gem_destroy:
 	vc4_gem_destroy(drm);
 	vc4_bo_cache_destroy(drm);
-dev_unref:
-	drm_dev_unref(drm);
+dev_put:
+	drm_dev_put(drm);
 	return ret;
 }
 
@@ -331,7 +331,7 @@ static void vc4_drm_unbind(struct device *dev)
 
 	drm_atomic_private_obj_fini(&vc4->ctm_manager);
 
-	drm_dev_unref(drm);
+	drm_dev_put(drm);
 }
 
 static const struct component_master_ops vc4_drm_ops = {