usbnet: smsc95xx: fix suspend failure

The three below functions:

	smsc95xx_enter_suspend0()
	smsc95xx_enter_suspend1()
	smsc95xx_enter_suspend2()

return > 0 in case of success, so they will cause smsc95xx_suspend()
to return > 0 and cause suspend failure.

The bug is introduced in commit 3b9f7d(smsc95xx: fix error handling
in suspend failure case).

Cc: <stable@vger.kernel.org>		[3.8]
Cc: Steve Glendinning <steve.glendinning@shawell.net>
Signed-off-by: Ming Lei <ming.lei@canonical.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/usb/smsc95xx.c

@@ -1247,10 +1247,12 @@ static int smsc95xx_enter_suspend0(struct usbnet *dev)
 
 	/* read back PM_CTRL */
 	ret = smsc95xx_read_reg_nopm(dev, PM_CTRL, &val);
+	if (ret < 0)
+		return ret;
 
 	pdata->suspend_flags |= SUSPEND_SUSPEND0;
 
-	return ret;
+	return 0;
 }
 
 static int smsc95xx_enter_suspend1(struct usbnet *dev)
@@ -1293,10 +1295,12 @@ static int smsc95xx_enter_suspend1(struct usbnet *dev)
 	val |= (PM_CTL_WUPS_ED_ | PM_CTL_ED_EN_);
 
 	ret = smsc95xx_write_reg_nopm(dev, PM_CTRL, val);
+	if (ret < 0)
+		return ret;
 
 	pdata->suspend_flags |= SUSPEND_SUSPEND1;
 
-	return ret;
+	return 0;
 }
 
 static int smsc95xx_enter_suspend2(struct usbnet *dev)
@@ -1313,10 +1317,12 @@ static int smsc95xx_enter_suspend2(struct usbnet *dev)
 	val |= PM_CTL_SUS_MODE_2;
 
 	ret = smsc95xx_write_reg_nopm(dev, PM_CTRL, val);
+	if (ret < 0)
+		return ret;
 
 	pdata->suspend_flags |= SUSPEND_SUSPEND2;
 
-	return ret;
+	return 0;
 }
 
 static int smsc95xx_enter_suspend3(struct usbnet *dev)