net: ngbe: convert phylib to phylink

Implement phylink in ngbe driver, to handle phy uniformly for Wangxun
ethernet devices.

Signed-off-by: Jiawen Wu <jiawenwu@trustnetic.com>
Reviewed-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>