fec: enable transmit and receive time stamping.

This patch has been tested on the Freescale M5234BCC, which includes the
National Semiconductor DP83640 with IEEE 1588 support.

Cc: Greg Ungerer <gerg@uclinux.org>
Cc: "Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>
Cc: Shawn Guo <shawn.guo@freescale.com>
Signed-off-by: Richard Cochran <richard.cochran@omicron.at>
Signed-off-by: David S. Miller <davem@conan.davemloft.net>