ALSA: usb-audio - Apply Logitech QuickCam Pro 9000 quirk only to audio iface

... instead of applying to all interfaces.

Reference: http://forums.gentoo.org/viewtopic-p-6886404.html

Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>