BugLink: http://bugs.launchpad.net/bugs/559065

In fec open/close function, we need to use phy_connect and phy_disconnect
operation before we start/stop phy. Otherwise it will cause system hang.

Only call fec_enet_mii_probe() in open function, because the first open
action will cause NULL pointer error.
Signed-off-by: NBryan Wu <bryan.wu@canonical.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>