ALSA: bebob: fix wrong decoding of clock information for Terratec PHASE 88 Rack FW

Terratec PHASE 88 rack fw has two registers for source of clock, one is
for internal/external, and another is for wordclock/spdif for external.

When clock source is internal, information in another register has no meaning.
Thus it must be ignored, but current implementation decodes it. This causes
over-indexing reference to labels.
Reported-by: NAndrás Murányi <muranyia@gmail.com>
Tested-by: NAndrás Murányi <muranyia@gmail.com>
Signed-off-by: NTakashi Sakamoto <o-takashi@sakamocchi.jp>
Acked-by: NClemens Ladisch <clemens@ladisch.de>
Signed-off-by: NTakashi Iwai <tiwai@suse.de>

sound/firewire/bebob/bebob_terratec.c

@@ -24,7 +24,12 @@ phase88_rack_clk_src_get(struct snd_bebob *bebob, unsigned int *id)
 	if (err < 0)
 		goto end;
 
-	*id = (enable_ext & 0x01) | ((enable_word & 0x01) << 1);
+	if (enable_ext == 0)
+		*id = 0;
+	else if (enable_word == 0)
+		*id = 1;
+	else
+		*id = 2;
 end:
 	return err;
 }