PCH_GbE : Fixed the issue of collision detection

PCH_GbE : Fixed the issue of collision detection

BugLink: http://bugs.launchpad.net/bugs/788691

commit ce3dad0f74e6b240f0b1dedbd8ea268a3f298d82 upstream.

The collision detection setting was invalid.
When collision occurred, because data was not resent,
there was an issue to which a transmitting throughput falls.

This patch enables the collision detection.

Signed-off-by: Toshiharu Okada <toshiharu-linux@dsn.okisemi.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Steve Conklin <sconklin@canonical.com>