net: phy: Log only PHY state transitions

In the current code, old and new PHY states are always logged.
>From now on, log only PHY state transitions.
Signed-off-by: Marc Gonzalez <marc_gonzalez@sigmadesigns.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/phy/phy.c

@@ -1225,9 +1225,10 @@ void phy_state_machine(struct work_struct *work)
 	if (err < 0)
 		phy_error(phydev);
 
-	phydev_dbg(phydev, "PHY state change %s -> %s\n",
-		   phy_state_to_str(old_state),
-		   phy_state_to_str(phydev->state));
+	if (old_state != phydev->state)
+		phydev_dbg(phydev, "PHY state change %s -> %s\n",
+			   phy_state_to_str(old_state),
+			   phy_state_to_str(phydev->state));
 
 	/* Only re-schedule a PHY state machine change if we are polling the
 	 * PHY, if PHY_IGNORE_INTERRUPT is set, then we will be moving