ALSA: bebob: apply new enumerator to normalize the type of clock source

Previous commit allows this driver to detect several types of clock
source, while there's no normalized expression for it.

This commit adds a new enumerator for this purpose.
Signed-off-by: NTakashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: NTakashi Iwai <tiwai@suse.de>

sound/firewire/bebob/bebob.h

@@ -50,9 +50,15 @@ extern const unsigned int snd_bebob_rate_table[SND_BEBOB_STRM_FMT_ENTRIES];
 
 /* device specific operations */
 #define SND_BEBOB_CLOCK_INTERNAL	"Internal"
+enum snd_bebob_clock_type {
+	SND_BEBOB_CLOCK_TYPE_INTERNAL = 0,
+	SND_BEBOB_CLOCK_TYPE_EXTERNAL,
+	SND_BEBOB_CLOCK_TYPE_SYT,
+};
 struct snd_bebob_clock_spec {
 	unsigned int num;
 	const char *const *labels;
+	enum snd_bebob_clock_type *types;
 	int (*get)(struct snd_bebob *bebob, unsigned int *id);
 };
 struct snd_bebob_rate_spec {