via-velocity: Add ethtool interrupt coalescing support

(Partially from the upstream VIA driver). Tweaking the number of
frames-per-interrupt and timer-until-interrupt can reduce the amount of
CPU work quite a lot.

Signed-off-by: Simon Kagstrom <simon.kagstrom@netinsight.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/via-velocity.h b/drivers/net/via-velocity.h
index ce894ff..499da64 100644
--- a/drivers/net/via-velocity.h
+++ b/drivers/net/via-velocity.h
@@ -1005,7 +1005,8 @@
 
 	volatile __le32 RDBaseLo;	/* 0x38 */
 	volatile __le16 RDIdx;		/* 0x3C */
-	volatile __le16 reserved_3E;
+	volatile u8 TQETMR;		/* 0x3E, VT3216 and above only */
+	volatile u8 RQETMR;		/* 0x3F, VT3216 and above only */
 
 	volatile __le32 TDBaseLo[4];	/* 0x40 */
 
@@ -1491,6 +1492,10 @@
 	int rx_bandwidth_hi;
 	int rx_bandwidth_lo;
 	int rx_bandwidth_en;
+	int rxqueue_timer;
+	int txqueue_timer;
+	int tx_intsup;
+	int rx_intsup;
 	u32 flags;
 };