ALSA: usb-audio: handle "Fast Track Ultra" with USB_DEVICE_VENDOR_SPEC()

That way, the class compliant MIDI interface is also handled.

Signed-off-by: Daniel Mack <zonque@gmail.com>
Reported-and-tested-by: Grant Diffey <gdiffey@gmail.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>