ip6mr: remove stray rcu_read_unlock() from ip6_mr_forward()

One rcu_read_unlock() should have been removed in blamed commit.

Fixes: 9b1c21d8 ("ip6mr: do not acquire mrt_lock while calling ip6_mr_forward()")
Reported-by: Vladimir Oltean <olteanv@gmail.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Vladimir Oltean <olteanv@gmail.com>
Link: https://lore.kernel.org/r/20220725200554.2563581-1-eric.dumazet@gmail.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

net/ipv6/ip6mr.c

@@ -2133,11 +2133,9 @@ static void ip6_mr_forward(struct net *net, struct mr_table *mrt,
 		 */
 		cache_proxy = mr_mfc_find_any_parent(mrt, vif);
 		if (cache_proxy &&
-		    cache_proxy->_c.mfc_un.res.ttls[true_vifi] < 255) {
-			rcu_read_unlock();
+		    cache_proxy->_c.mfc_un.res.ttls[true_vifi] < 255)
 			goto forward;
 	}
-	}
 
 	/*
 	 * Wrong interface: drop packet and (maybe) send PIM assert.