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 void snd_usbmidi_standard_input(struct snd_usb_midi_in_endpoint *ep,
				       uint8_t *buffer, int buffer_length)
{
	int i;

	for (i = 0; i + 3 < buffer_length; i += 4)
		if (buffer[i] != 0) {
			int cable = buffer[i] >> 4;
			int length = snd_usbmidi_cin_length[buffer[i] & 0x0f];
			snd_usbmidi_input_data(ep, cable, &buffer[i + 1],
					       length);
		}
}

static void snd_usbmidi_standard_input(struct snd_usb_midi_in_endpoint *ep,
				       uint8_t *buffer, int buffer_length)
{
	int i;

	for (i = 0; i + 3 < buffer_length; i += 4)
		if (buffer[i] != 0) {
			int cable = buffer[i] >> 4;
			int length = snd_usbmidi_cin_length[buffer[i] & 0x0f];
			snd_usbmidi_input_data(ep, cable, &buffer[i + 1],
					       length);
		}
}
