net: fib: fix incorrect call_rcu_bh()

After IP route cache removal, I believe rcu_bh() has very little use and
we should remove this RCU variant, since it adds some cycles in fast
path.

Anyway, the call_rcu_bh() use in fib_true is obviously wrong, since
some users only assert rcu_read_lock().

Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv4/fib_trie.c

@@ -367,7 +367,7 @@ static void __leaf_free_rcu(struct rcu_head *head)
 
 static inline void free_leaf(struct leaf *l)
 {
-	call_rcu_bh(&l->rcu, __leaf_free_rcu);
+	call_rcu(&l->rcu, __leaf_free_rcu);
 }
 
 static inline void free_leaf_info(struct leaf_info *leaf)