phylib: Add of_phy_attach

10G PHYs don't currently support running the state machine, which
is implicitly setup via of_phy_connect(). Therefore, it is necessary
to implement an OF version of phy_attach(), which does everything
except start the state machine.

Signed-off-by: Andy Fleming <afleming@gmail.com>
Signed-off-by: Shaohui Xie <Shaohui.Xie@freescale.com>
Acked-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>