net: phy: Manual remove LEDs to ensure correct ordering

If the core is left to remove the LEDs via devm_, it is performed too
late, after the PHY driver is removed from the PHY. This results in
dereferencing a NULL pointer when the LED core tries to turn the LED
off before destroying the LED.

Manually unregister the LEDs at a safe point in phy_remove.

Cc: stable@vger.kernel.org
Reported-by: Florian Fainelli <f.fainelli@gmail.com>
Suggested-by: Florian Fainelli <f.fainelli@gmail.com>
Fixes: 01e5b728 ("net: phy: Add a binding for PHY LEDs")
Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>