Make sure to drop references taken and deregister devices registered
during probe on probe errors (including deferred probe) and driver
unbind.

Specifically, PHY of-node references were never released and fixed-link
PHY devices were never deregistered.

Fixes: 9e42f715 ("drivers: net: cpsw: add phy-handle parsing")
Fixes: 1f71e8c9 ("drivers: net: cpsw: Add support for fixed-link
PHY")
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>