ALSA: usb-audio: avoid freeing umidi object twice

The 'umidi' object will be free'd on the error path by snd_usbmidi_free()
when tearing down the rawmidi interface. So we shouldn't try to free it
in snd_usbmidi_create() after having registered the rawmidi interface.

Found by KASAN.

Signed-off-by: Andrey Konovalov <andreyknvl@gmail.com>
Acked-by: Clemens Ladisch <clemens@ladisch.de>
Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
static int roland_load_put(struct snd_kcontrol *kcontrol,
			   struct snd_ctl_elem_value *value)
{
	struct snd_usb_midi *umidi = kcontrol->private_data;
	int changed;

	if (value->value.enumerated.item[0] > 1)
		return -EINVAL;
	mutex_lock(&umidi->mutex);
	changed = value->value.enumerated.item[0] != kcontrol->private_value;
	if (changed)
		kcontrol->private_value = value->value.enumerated.item[0];
	mutex_unlock(&umidi->mutex);
	return changed;
}

static int roland_load_put(struct snd_kcontrol *kcontrol,
			   struct snd_ctl_elem_value *value)
{
	struct snd_usb_midi *umidi = kcontrol->private_data;
	int changed;

	if (value->value.enumerated.item[0] > 1)
		return -EINVAL;
	mutex_lock(&umidi->mutex);
	changed = value->value.enumerated.item[0] != kcontrol->private_value;
	if (changed)
		kcontrol->private_value = value->value.enumerated.item[0];
	mutex_unlock(&umidi->mutex);
	return changed;
}
