dma-buf: Replace PTR_RET with PTR_ERR_OR_ZERO

PTR_RET is now deprecated. Use PTR_ERR_OR_ZERO instead.

Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
diff --git a/drivers/base/dma-buf.c b/drivers/base/dma-buf.c
index 6687ba7..1219ab7 100644
--- a/drivers/base/dma-buf.c
+++ b/drivers/base/dma-buf.c
@@ -680,7 +680,7 @@
 	d = debugfs_create_file(name, S_IRUGO, dma_buf_debugfs_dir,
 			write, &dma_buf_debug_fops);
 
-	return PTR_RET(d);
+	return PTR_ERR_OR_ZERO(d);
 }
 #else
 static inline int dma_buf_init_debugfs(void)