bonding: comparing a u8 with -1 is always false

slave->duplex is a u8 type so the in bond_info_show_slave() when we
check "if (slave->duplex == -1)", it's always false.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
index b2b9109..b0c5772 100644
--- a/drivers/net/bonding/bond_main.c
+++ b/drivers/net/bonding/bond_main.c
@@ -560,8 +560,8 @@
 	u32 slave_speed;
 	int res;
 
-	slave->speed = -1;
-	slave->duplex = -1;
+	slave->speed = SPEED_UNKNOWN;
+	slave->duplex = DUPLEX_UNKNOWN;
 
 	res = __ethtool_get_settings(slave_dev, &ecmd);
 	if (res < 0)