ALSA: usb-audio: avoid freeing umidi object twice

ALSA: usb-audio: avoid freeing umidi object twice

Orabug: 22740866
CVE: CVE-2016-2384

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>
(cherry picked from commit 07d86ca93db7e5cdf4743564d98292042ec21af7)
Signed-off-by: Brian Maly <brian.maly@oracle.com>