drm/nouveau/debugfs: fix file release memory leak

When using single_open() for opening, single_release() should be
called, otherwise the 'op' allocated in single_open() will be leaked.

Fixes: 6e9fc17 ("drm/nouveau/debugfs: add copy of sysfs pstate interface ported to debugfs")
Reported-by: Hulk Robot <[email protected]>
Signed-off-by: Yang Yingliang <[email protected]>
Reviewed-by: Karol Herbst <[email protected]>
Signed-off-by: Karol Herbst <[email protected]>
Link: https://patchwork.freedesktop.org/patch/msgid/[email protected]
Signed-off-by: Maarten Lankhorst <[email protected]>

Author: Yang Yingliang

drivers/gpu/drm/nouveau/nouveau_debugfs.c

@@ -207,6 +207,7 @@ static const struct file_operations nouveau_pstate_fops = {
 	.open = nouveau_debugfs_pstate_open,
 	.read = seq_read,
 	.write = nouveau_debugfs_pstate_set,
+	.release = single_release,
 };
 
 static struct drm_info_list nouveau_debugfs_list[] = {