i2c: mux: demux-pinctrl: Convert to use sysfs_emit_at() API

Follow the advice of the Documentation/filesystems/sysfs.rst and show()
should only use sysfs_emit() or sysfs_emit_at() when formatting the
value to be returned to user space.
Signed-off-by: ye xingchen <ye.xingchen@zte.com.cn>
Tested-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
[wsa: proper subject prefix]
Signed-off-by: Wolfram Sang <wsa@kernel.org>

drivers/i2c/muxes/i2c-demux-pinctrl.c

@@ -167,9 +167,9 @@ static ssize_t available_masters_show(struct device *dev,
 	int count = 0, i;
 
 	for (i = 0; i < priv->num_chan && count < PAGE_SIZE; i++)
-		count += scnprintf(buf + count, PAGE_SIZE - count, "%d:%pOF%c",
-				   i, priv->chan[i].parent_np,
-				   i == priv->num_chan - 1 ? '\n' : ' ');
+		count += sysfs_emit_at(buf, count, "%d:%pOF%c",
+				       i, priv->chan[i].parent_np,
+				       i == priv->num_chan - 1 ? '\n' : ' ');
 
 	return count;
 }