tg3: Always turn on APE features in mac_mode reg

The APE needs certain bits in the mac_mode register to be enabled for
traffic to flow correctly.  This patch changes the code to always enable
these bits in the presence of the APE.

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