forcedeth: mac address fix

This critical patch fixes a mac address issue recently introduced.  If the
device's mac address was in correct order and the flag
NVREG_TRANSMITPOLL_MAC_ADDR_REV was set, during nv_remove the flag would get
cleared.  During next load, the mac address would get reversed because the
flag is missing.

As it has been indicated previously, the flag is cleared across a low power
transition.  Therefore, the driver should set the mac address back into the
reversed order when clearing the flag.

Also, the driver should set back the flag after a low power transition to
protect against kexec command calling nv_probe a second time.

Signed-off-by: Ayaz Abdulla <aabdulla@nvidia.com>
Cc: "Yinghai Lu" <yhlu.kernel@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>