ethoc: clear only pending irqs

This patch fixed the problem of dropped packets due to lost of
interrupt requests. We should only clear what was pending at the
moment we read the irq source reg.

Signed-off-by: Thomas Chou <thomas@wytron.com.tw>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/ethoc.c b/drivers/net/ethoc.c
index 88a1c52..590473a 100644
--- a/drivers/net/ethoc.c
+++ b/drivers/net/ethoc.c
@@ -508,7 +508,7 @@
 		return IRQ_NONE;
 	}
 
-	ethoc_ack_irq(priv, INT_MASK_ALL);
+	ethoc_ack_irq(priv, pending);
 
 	if (pending & INT_MASK_BUSY) {
 		dev_err(&dev->dev, "packet dropped\n");