ALSA: oxfw: move model-specific members from common structure

Currently, 'struct snd_oxfw' has some members for models supported by old
firewire-speakers driver, while these members are useless to the other
models.

This commit allocates new memory block and moves these members to
model-specific structure.

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

sound/firewire/oxfw/oxfw.h

@@ -64,11 +64,6 @@ struct snd_oxfw {
 	unsigned int midi_input_ports;
 	unsigned int midi_output_ports;
 
-	bool mute;
-	s16 volume[6];
-	s16 volume_min;
-	s16 volume_max;
-
 	int dev_lock_count;
 	bool dev_lock_changed;
 	wait_queue_head_t hwdep_wait;