net: txgbe: use phylink bits added in libwx

Convert txgbe to use phylink and phylink_config added in libwx.

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>