rbd: add parentheses to object request iterator macros

The for_each_obj_request*() macros should parenthesize their uses of
the ireq parameter.

Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
index 13ee789..ff9e925 100644
--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -226,11 +226,11 @@
 };
 
 #define for_each_obj_request(ireq, oreq) \
-	list_for_each_entry(oreq, &ireq->obj_requests, links)
+	list_for_each_entry(oreq, &(ireq)->obj_requests, links)
 #define for_each_obj_request_from(ireq, oreq) \
-	list_for_each_entry_from(oreq, &ireq->obj_requests, links)
+	list_for_each_entry_from(oreq, &(ireq)->obj_requests, links)
 #define for_each_obj_request_safe(ireq, oreq, n) \
-	list_for_each_entry_safe_reverse(oreq, n, &ireq->obj_requests, links)
+	list_for_each_entry_safe_reverse(oreq, n, &(ireq)->obj_requests, links)
 
 struct rbd_snap {
 	struct	device		dev;