ALSA: usb-audio: dynamic detection of MIDI interfaces in uaxx-quirk

The MIDI interfaces have to be detected dynamically for Edirol devices
ua-700, ua-25 and ua4-fx. This patch reverses the wrong changes made by
my other patch in uaxx-quirk.

Signed-off-by: Pedro Lopez-Cabanillas <pedro.lopez.cabanillas@gmail.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Jaroslav Kysela <perex@perex.cz>