[TG3]: add amd8131 to "write reorder" chipsets

Add the AMD 8131 bridge to the list of chipsets that reorder writes.

Signed-off-by: John W. Linville <linville@tuxdriver.com>
Acked-by: Michael Chan <mchan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>