USB: quirks: Fix another ELAN touchscreen

Like other buggy models that had their fixes [1], the touchscreen with
id 04f3:21b8 from ELAN Microelectronics needs the device-qualifier
quirk. Otherwise, it fails to respond, blocks the boot for a random
amount of time and pollutes dmesg with:

[ 2887.373196] usb 1-5: new full-speed USB device number 41 using xhci_hcd
[ 2889.502000] usb 1-5: unable to read config index 0 descriptor/start: -71
[ 2889.502005] usb 1-5: can't read configurations, error -71
[ 2889.654571] usb 1-5: new full-speed USB device number 42 using xhci_hcd
[ 2891.783438] usb 1-5: unable to read config index 0 descriptor/start: -71
[ 2891.783443] usb 1-5: can't read configurations, error -71

[1]: See commits c68929f, 876af5d, d749947, a32c99e and dc703ec.

Tested-by: Adrien Vergé <adrienverge@gmail.com>
Signed-off-by: Adrien Vergé <adrienverge@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/core/quirks.c

@@ -125,6 +125,9 @@ static const struct usb_device_id usb_quirk_list[] = {
 	{ USB_DEVICE(0x04f3, 0x016f), .driver_info =
 			USB_QUIRK_DEVICE_QUALIFIER },
 
+	{ USB_DEVICE(0x04f3, 0x21b8), .driver_info =
+			USB_QUIRK_DEVICE_QUALIFIER },
+
 	/* Roland SC-8820 */
 	{ USB_DEVICE(0x0582, 0x0007), .driver_info = USB_QUIRK_RESET_RESUME },