xen: make use of xenbus_read_unsigned() in xen-fbfront

Use xenbus_read_unsigned() instead of xenbus_scanf() when possible.
This requires to change the type of the reads from int to unsigned,
but these cases have been wrong before: negative values are not allowed
for the modified cases.

Cc: [e-mail]
Cc: [e-mail]

Signed-off-by: Juergen Gross <[e-mail]>
Acked-by: David Vrabel <[e-mail]>

drivers/video/fbdev/xen-fbfront.c

···
 				  enum xenbus_state backend_state)
 {
 	struct xenfb_info *info = dev_get_drvdata(&dev->dev);
-	int val;
 
 	switch (backend_state) {
 	case XenbusStateInitialising:
···
 		if (dev->state != XenbusStateConnected)
 			goto InitWait; /* no InitWait seen yet, fudge it */
 
-		if (xenbus_scanf(XBT_NIL, info->xbdev->otherend,
-				 "request-update", "%d", &val) < 0)
-			val = 0;
-		if (val)
+		if (xenbus_read_unsigned(info->xbdev->otherend,
+					 "request-update", 0))
 			info->update_wanted = 1;
 
-		if (xenbus_scanf(XBT_NIL, dev->otherend,
-				 "feature-resize", "%d", &val) < 0)
-			val = 0;
-		info->feature_resize = val;
+		info->feature_resize = xenbus_read_unsigned(dev->otherend,
+							"feature-resize", 0);
 		break;
 
 	case XenbusStateClosed: