[ALSA] usb-audio: explicitly match Logitech QuickCam

Commit 93c8bf45e0 modified the USB device
matching behaviour to ignore interface class matches if the device class
is vendor-specific.
This patch adds explicit ID matches for Logitech QuickCam devices, which
have a vendor specific device class (but standards-compliant audio
interfaces).
This fixes a 2.6.20 regression where the audio component of these
devices was no longer usable.
http://bugs.gentoo.org/show_bug.cgi?id=175715
https://bugs.launchpad.net/ubuntu/+source/linux-source-2.6.20/+bug/93822
https://bugtrack.alsa-project.org/alsa-bug/view.php?id=3040
Based on a patch from sergiom

Signed-off-by: Daniel Drake <dsd@gentoo.org>
Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Jaroslav Kysela <perex@suse.cz>

sound/usb/usbquirks.h

@@ -39,6 +39,29 @@
 	.idProduct = prod, \
 	.bInterfaceClass = USB_CLASS_VENDOR_SPEC
 
+/*
+ * Logitech QuickCam: bDeviceClass is vendor-specific, so generic interface
+ * class matches do not take effect without an explicit ID match.
+ */
+{
+	.match_flags = USB_DEVICE_ID_MATCH_DEVICE |
+		       USB_DEVICE_ID_MATCH_INT_CLASS |
+		       USB_DEVICE_ID_MATCH_INT_SUBCLASS,
+	.idVendor = 0x046d,
+	.idProduct = 0x08f0,
+	.bInterfaceClass = USB_CLASS_AUDIO,
+	.bInterfaceSubClass = USB_SUBCLASS_AUDIO_CONTROL
+},
+{
+	.match_flags = USB_DEVICE_ID_MATCH_DEVICE |
+		       USB_DEVICE_ID_MATCH_INT_CLASS |
+		       USB_DEVICE_ID_MATCH_INT_SUBCLASS,
+	.idVendor = 0x046d,
+	.idProduct = 0x08f6,
+	.bInterfaceClass = USB_CLASS_AUDIO,
+	.bInterfaceSubClass = USB_SUBCLASS_AUDIO_CONTROL
+},
+
 /*
  * Yamaha devices
  */