sh_eth: handle only enabled E-MAC interrupts

The driver should only handle the enabled E-MAC interrupts, like it does
for the E-DMAC interrupts since commit 3893b273 ("sh_eth: workaround
for spurious ECI interrupt"),  so mask ECSR with  ECSIPR when reading it
in sh_eth_error().
Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/renesas/sh_eth.c

@@ -1535,7 +1535,8 @@ static void sh_eth_error(struct net_device *ndev, u32 intr_status)
 	u32 mask;
 
 	if (intr_status & EESR_ECI) {
-		felic_stat = sh_eth_read(ndev, ECSR);
+		felic_stat = sh_eth_read(ndev, ECSR) &
+			     sh_eth_read(ndev, ECSIPR);
 		sh_eth_write(ndev, felic_stat, ECSR);	/* clear int */
 		if (felic_stat & ECSR_ICD)
 			ndev->stats.tx_carrier_errors++;