bonding: convert downdelay to use the new option API

This patch adds the necessary changes so downdelay would use
the new bonding option API. Also some trivial style fixes.

Signed-off-by: Nikolay Aleksandrov <nikolay@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/bonding/bond_sysfs.c b/drivers/net/bonding/bond_sysfs.c
index 5eeb3a2..b4f6713 100644
--- a/drivers/net/bonding/bond_sysfs.c
+++ b/drivers/net/bonding/bond_sysfs.c
@@ -501,22 +501,13 @@
 				       struct device_attribute *attr,
 				       const char *buf, size_t count)
 {
-	int new_value, ret;
 	struct bonding *bond = to_bond(d);
+	int ret;
 
-	if (sscanf(buf, "%d", &new_value) != 1) {
-		pr_err("%s: no down delay value specified.\n", bond->dev->name);
-		return -EINVAL;
-	}
-
-	if (!rtnl_trylock())
-		return restart_syscall();
-
-	ret = bond_option_downdelay_set(bond, new_value);
+	ret = bond_opt_tryset_rtnl(bond, BOND_OPT_DOWNDELAY, (char *)buf);
 	if (!ret)
 		ret = count;
 
-	rtnl_unlock();
 	return ret;
 }
 static DEVICE_ATTR(downdelay, S_IRUGO | S_IWUSR,