netdev/fec.c: add phylib supporting to enable carrier detection (v2)

netdev/fec.c: add phylib supporting to enable carrier detection (v2)

BugLink: http://bugs.launchpad.net/bugs/457878
v2:
 - remove duplicated phy_speed caculation
 - fix the phy_speed caculation according to the DataSheet

v1:
 - removed old MII phy control code
 - add phylib supporting
 - add ethtool interface to make user space NetworkManager works

Tested on Freescale i.MX51 Babbage board.

This patch is based on a patch from Frederic Rodo <[email protected]>

Cc: Frederic Rodo <[email protected]>
Signed-off-by: Bryan Wu <[email protected]>
Acked-by: Amit Kucheria <[email protected]>
Acked-by: Sascha Hauer <[email protected]>
Signed-off-by: David S. Miller <[email protected]>