tg3: Reenable TSS for 5719

All TSS bugs have been fixed in the 5719.  This patch reenables the
feature.

Signed-off-by: Matt Carlson <mcarlson@broadcom.com>
Reviewed-by: Michael Chan <mchan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>