ALSA: usb-audio: Add MIDI quirk for Vox ToneLab EX

ToneLab EX guitar pedal device requires the same quirk like ToneLab ST
for supporting the MIDI.

BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=212593
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20210407144549.1530-1-tiwai@suse.de


Signed-off-by: Takashi Iwai <tiwai@suse.de>