tg3: 5701 DMA corruption fix

Herbert Xu's commit fb93134dfc2a6e6fbedc7c270a31da03fce88db9, entitled
"[TCP]: Fix size calculation in sk_stream_alloc_pskb", has triggered a
bug in the 5701 where the 5701 DMA engine will corrupt outgoing
packets.  This problem only happens when the starting address of the
packet matches a certain range of offsets and only when the 5701 is
placed downstream of a particular Intel bridge.

This patch detects the problematic bridge and if present, readjusts the
starting address of the packet data to a dword aligned boundary.

Signed-off-by: Matt Carlson <mcarlson@broadcom.com>
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 c1075a7..c688c3a 100644
--- a/drivers/net/tg3.h
+++ b/drivers/net/tg3.h
@@ -2476,6 +2476,7 @@
 #define TG3_FLG3_NO_NVRAM_ADDR_TRANS	0x00000001
 #define TG3_FLG3_ENABLE_APE		0x00000002
 #define TG3_FLG3_5761_5784_AX_FIXES	0x00000004
+#define TG3_FLG3_5701_DMA_BUG		0x00000008
 
 	struct timer_list		timer;
 	u16				timer_counter;