With previous commit, this module managed to leave the counting to each
drivers, but the isochronous resources functionality still increment/decrement
the count.
This commit purge such codes to leave the responsibility to each drivers.
Fix: 
c6f224dc20ad ('ALSA: firewire-lib: remove reference counting')
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
 int fw_iso_resources_init(struct fw_iso_resources *r, struct fw_unit *unit)
 {
        r->channels_mask = ~0uLL;
-       r->unit = fw_unit_get(unit);
+       r->unit = unit;
        mutex_init(&r->mutex);
        r->allocated = false;
 
 {
        WARN_ON(r->allocated);
        mutex_destroy(&r->mutex);
-       fw_unit_put(r->unit);
 }
 EXPORT_SYMBOL(fw_iso_resources_destroy);