[TG3]: Add rx BD workaround

Add workaround to limit the burst size of rx BDs being DMA'ed to the
chip.  This works around hardware errata on a number of 5750, 5752,
and 5755 chips.

Signed-off-by: Michael Chan <mchan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/tg3.h b/drivers/net/tg3.h
index 8209da5..e9177f8 100644
--- a/drivers/net/tg3.h
+++ b/drivers/net/tg3.h
@@ -2137,6 +2137,7 @@
 	struct tg3_rx_buffer_desc	*rx_std;
 	struct ring_info		*rx_std_buffers;
 	dma_addr_t			rx_std_mapping;
+	u32				rx_std_max_post;
 
 	struct tg3_rx_buffer_desc	*rx_jumbo;
 	struct ring_info		*rx_jumbo_buffers;