ASoC: Don't set invalid name string to snd_card->driver field

The snd_card->driver field contains a driver name string, and in
general it shouldn't contain space or special letters.  The commit
2b39535b9e54888649923beaab443af212b6c0fd changed the string copy from
card->name, but the long name string may contain such letters, thus
it may still lead to a segfault.

A temporary fix is not to copy the long name string but just keep it
empty as the earlier version did.

Reported-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Acked-by: Liam Girdwood <lrg@ti.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/soc/soc-core.c

@@ -1929,8 +1929,9 @@ static void snd_soc_instantiate_card(struct snd_soc_card *card)
 		 "%s", card->name);
 	snprintf(card->snd_card->longname, sizeof(card->snd_card->longname),
 		 "%s", card->long_name ? card->long_name : card->name);
-	snprintf(card->snd_card->driver, sizeof(card->snd_card->driver),
-		 "%s", card->driver_name ? card->driver_name : card->name);
+	if (card->driver_name)
+		strlcpy(card->snd_card->driver, card->driver_name,
+			sizeof(card->snd_card->driver));
 
 	if (card->late_probe) {
 		ret = card->late_probe(card);