ALSA: fireface: share helper function to get current sampling rate and clock source

As long as investigating packet dumps from Fireface 400/800, bits on
status registers for clock synchronization are the same.

This commit moves a parser for a register of clock configuration to
obsolete model-specific operations.

Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/firewire/fireface/ff-pcm.c

@@ -141,7 +141,7 @@ static int pcm_open(struct snd_pcm_substream *substream)
 	if (err < 0)
 		goto release_lock;
 
-	err = ff->spec->protocol->get_clock(ff, &rate, &src);
+	err = snd_ff_transaction_get_clock(ff, &rate, &src);
 	if (err < 0)
 		goto release_lock;