net: phy: export phy_start_machine() for phylink

phylink will need phy_start_machine exported, so lets export it as a
GPL symbol.  Documentation/networking/phy.txt indicates that this
should be a PHY API function.
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/phy/phy.c

@@ -556,6 +556,7 @@ void phy_start_machine(struct phy_device *phydev)
 {
 	queue_delayed_work(system_power_efficient_wq, &phydev->state_queue, HZ);
 }
+EXPORT_SYMBOL_GPL(phy_start_machine);
 
 /**
  * phy_trigger_machine - trigger the state machine to run