ALSA: seq: correctly report maximum number of ports

Due to SNDRV_SEQ_ADDRESS_BROADCAST, not all 256 port number values can
be used.
Signed-off-by: NClemens Ladisch <clemens@ladisch.de>
Signed-off-by: NTakashi Iwai <tiwai@suse.de>

sound/core/seq/seq_clientmgr.c

@@ -1133,7 +1133,7 @@ static int snd_seq_ioctl_system_info(struct snd_seq_client *client, void __user
 	/* fill the info fields */
 	info.queues = SNDRV_SEQ_MAX_QUEUES;
 	info.clients = SNDRV_SEQ_MAX_CLIENTS;
-	info.ports = 256;	/* fixed limit */
+	info.ports = SNDRV_SEQ_MAX_PORTS;
 	info.channels = 256;	/* fixed limit */
 	info.cur_clients = client_usage.cur;
 	info.cur_queues = snd_seq_queue_get_cur_queues();