USB: adutux: fix interface sanity check

USB: adutux: fix interface sanity check

commit 3c11c4bed02b202e278c0f5c319ae435d7fb9815 upstream.

Make sure to use the current alternate setting when verifying the
interface descriptors to avoid binding to an invalid interface.

Failing to do so could cause the driver to misbehave or trigger a WARN()
in usb_submit_urb() that kernels with panic_on_warn set would choke on.

Fixes: 03270634e242 ("USB: Add ADU support for Ontrak ADU devices")
Cc: stable <stable@vger.kernel.org>     # 2.6.19
Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20191210112601.3561-3-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>