snd_device_register — register the device
int snd_device_register (struct snd_card * card, void * device_data);
Registers the device which was already created via
snd_device_new. Usually this is called from snd_card_register,
but it can be called later if any new devices are created after
invocation of snd_card_register.
Returns zero if successful, or a negative error code on failure or if the device not found.