tg3: Lay proucer ring handling groundwork

The patch increases the number of producer rings available and
implements the constructor and destructor code that deals with them.

Signed-off-by: Matt Carlson <mcarlson@broadcom.com>
Reviewed-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 e0b86ba..715df2b 100644
--- a/drivers/net/tg3.h
+++ b/drivers/net/tg3.h
@@ -2682,7 +2682,7 @@
 	struct vlan_group		*vlgrp;
 #endif
 
-	struct tg3_rx_prodring_set	prodring[1];
+	struct tg3_rx_prodring_set	prodring[TG3_IRQ_MAX_VECS - 1];
 
 
 	/* begin "everything else" cacheline(s) section */