char: virtio: 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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/char/virtio_console.c

@@ -1309,7 +1309,7 @@ static const struct attribute_group port_attribute_group = {
 	.attrs = port_sysfs_entries,
 };
 
-static int debugfs_show(struct seq_file *s, void *data)
+static int port_debugfs_show(struct seq_file *s, void *data)
 {
 	struct port *port = s->private;
 
@@ -1327,18 +1327,7 @@ static int debugfs_show(struct seq_file *s, void *data)
 	return 0;
 }
 
-static int debugfs_open(struct inode *inode, struct file *file)
-{
-	return single_open(file, debugfs_show, inode->i_private);
-}
-
-static const struct file_operations port_debugfs_ops = {
-	.owner = THIS_MODULE,
-	.open = debugfs_open,
-	.read = seq_read,
-	.llseek = seq_lseek,
-	.release = single_release,
-};
+DEFINE_SHOW_ATTRIBUTE(port_debugfs);
 
 static void set_console_size(struct port *port, u16 rows, u16 cols)
 {
@@ -1490,7 +1479,7 @@ static int add_port(struct ports_device *portdev, u32 id)
 		port->debugfs_file = debugfs_create_file(debugfs_name, 0444,
 							 pdrvdata.debugfs_dir,
 							 port,
-							 &port_debugfs_ops);
+							 &port_debugfs_fops);
 	}
 	return 0;