[IPV4]: Fix thinko in fib_find_alias

fib_find_alias is meant to return either an exact match or the
entry just before where it should be.  Currently it returns the
entry after that.  This patch fixes that.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv4/fib_hash.c

@@ -448,7 +448,7 @@ static struct fib_alias *fib_find_alias(struct fib_node *fn, u8 tos, u32 prio)
 			if (prio <= fa->fa_info->fib_priority)
 				break;
 		}
-		return fa;
+		return prev_fa;
 	}
 	return NULL;
 }