dma-buf: Change to use DEFINE_SHOW_ATTRIBUTE macro

Use DEFINE_SHOW_ATTRIBUTE macro to simplify the code.

Signed-off-by: Yangtao Li <tiny.windzz@gmail.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20181130161101.3413-1-tiny.windzz@gmail.com
diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
index 02f7f9a..7c85802 100644
--- a/drivers/dma-buf/dma-buf.c
+++ b/drivers/dma-buf/dma-buf.c
@@ -1093,17 +1093,7 @@ static int dma_buf_debug_show(struct seq_file *s, void *unused)
 	return 0;
 }
 
-static int dma_buf_debug_open(struct inode *inode, struct file *file)
-{
-	return single_open(file, dma_buf_debug_show, NULL);
-}
-
-static const struct file_operations dma_buf_debug_fops = {
-	.open           = dma_buf_debug_open,
-	.read           = seq_read,
-	.llseek         = seq_lseek,
-	.release        = single_release,
-};
+DEFINE_SHOW_ATTRIBUTE(dma_buf_debug);
 
 static struct dentry *dma_buf_debugfs_dir;