ALSA: snd-usb: Accept UAC2 FORMAT_TYPE descriptors with bLength > 6

ALSA: snd-usb: Accept UAC2 FORMAT_TYPE descriptors with bLength > 6

commit 824818b148db42173446707df4cbd61cd7133272 upstream.

The Focusrite Scarlett 18i6 USB has them that way, which is probably a
bug. Anyway, the driver should simply ignore this fact.

Signed-off-by: Daniel Mack <zonque@gmail.com>
Reported-by: Nicolai Krakowiak <nicolai.krakowiak@gmail.com>
Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>