xen/blkback: fix white space code style issues

Signed-off-by: Juergen Gross <jgross@suse.com>
Acked-by: Roger Pau Monné <roger.pau@citrix.com>
Signed-off-by: Juergen Gross <jgross@suse.com>

drivers/block/xen-blkback/blkback.c

@@ -891,7 +891,7 @@ static int xen_blkbk_map(struct xen_blkif_ring *ring,
 out:
 	for (i = last_map; i < num; i++) {
 		/* Don't zap current batch's valid persistent grants. */
-		if(i >= map_until)
+		if (i >= map_until)
 			pages[i]->persistent_gnt = NULL;
 		pages[i]->handle = BLKBACK_INVALID_HANDLE;
 	}