rds: Fix improper gfp_t usage.

>> net/rds/ib_recv.c:382:28: sparse: incorrect type in initializer (different base types)
   net/rds/ib_recv.c:382:28:    expected int [signed] can_wait
   net/rds/ib_recv.c:382:28:    got restricted gfp_t
   net/rds/ib_recv.c:828:23: sparse: cast to restricted __le64

Reported-by: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/rds/ib_recv.c b/net/rds/ib_recv.c
index 3afdcbd..ed9b41e 100644
--- a/net/rds/ib_recv.c
+++ b/net/rds/ib_recv.c
@@ -379,7 +379,7 @@
 	struct ib_recv_wr *failed_wr;
 	unsigned int posted = 0;
 	int ret = 0;
-	int can_wait = gfp & __GFP_WAIT;
+	bool can_wait = !!(gfp & __GFP_WAIT);
 	u32 pos;
 
 	/* the goal here is to just make sure that someone, somewhere