mei: check for error codes that mei_flow_ctrl_creds retuns

we cannot use if(!mei_flow_ctrl_creds()) logic as
mei_flow_ctrl_creds also negative error codes

Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/misc/mei/interrupt.c

@@ -1326,7 +1326,7 @@ static int mei_irq_thread_write_handler(struct mei_io_list *cmpl_list,
 			continue;
 
 		if (cl != &dev->iamthif_cl) {
-			if (!mei_flow_ctrl_creds(dev, cl)) {
+			if (mei_flow_ctrl_creds(dev, cl) <= 0) {
 				dev_dbg(&dev->pdev->dev,
 					"No flow control"
 				    " credentials for client"
@@ -1343,7 +1343,7 @@ static int mei_irq_thread_write_handler(struct mei_io_list *cmpl_list,
 		} else if (cl == &dev->iamthif_cl) {
 			/* IAMTHIF IOCTL */
 			dev_dbg(&dev->pdev->dev, "complete amthi write cb.\n");
-			if (!mei_flow_ctrl_creds(dev, cl)) {
+			if (mei_flow_ctrl_creds(dev, cl) <= 0) {
 				dev_dbg(&dev->pdev->dev,
 					"No flow control"
 				    " credentials for amthi"