staging/rdma/hfi1: use RCU_INIT_POINTER() when NULLing.

It is safe to use RCU_INIT_POINTER() to NULL a pointer, instead of
rcu_assign_pointer().
This results in slightly smaller/faster code.
Signed-off-by: Muhammad Falak R Wani <falakreyaz@gmail.com>
Reviewed-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>

drivers/staging/rdma/hfi1/init.c

@@ -1300,7 +1300,7 @@ static void cleanup_device_data(struct hfi1_devdata *dd)
 
 		spin_lock(&ppd->cc_state_lock);
 		cc_state = get_cc_state(ppd);
-		rcu_assign_pointer(ppd->cc_state, NULL);
+		RCU_INIT_POINTER(ppd->cc_state, NULL);
 		spin_unlock(&ppd->cc_state_lock);
 
 		if (cc_state)