net: phy: phylink: Release link GPIO

We are not releasing the link GPIO descriptor with gpiod_put() which results in
subsequent probing to get -EBUSY when calling fwnode_get_named_gpiod(). Fix this
by doing the release in phylink_destroy().

Fixes: 9525ae83

 ("phylink: add phylink infrastructure")
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>