Revert "cdc-acm: hardening against malicious devices"

This reverts commit 2ad9d544.

Drop bogus sanity check; an interface in the active configuration will
always have a current altsetting assigned by USB core.

Acked-by: Oliver Neukum <oneukum@suse.com>
Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20200921135951.24045-2-johan@kernel.org


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>