phy: fix device reference leaks

Make sure to drop the reference taken by bus_find_device_by_name()
before returning from phy_connect() and phy_attach().

Note that both function still take a reference to the phy device
through phy_attach_direct().

Fixes: e1393456

 ("[PATCH] PHY Layer fixup")
Cc: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>