phy: fix error case of phy_led_triggers_(un)register

When phy_init_hw() fails at phy_attach_direct();
- phy_detach() calls phy_led_triggers_unregister() without
  previous call of phy_led_triggers_register().
- still call phy_led_triggers_register() and cause memory leak.

Fixes: 2e0bc452

 ("net: phy: leds: add support for led triggers on phy link state change")
Signed-off-by: Woojung Huh <woojung.huh@microchip.com>
Signed-off-by: David S. Miller <davem@davemloft.net>