USB: option: Added support for Samsung GT-B3730/GT-B3710 LTE USB modem.

Bind only modem AT command endpoint to option.

Signed-off-by: Marius B. Kotsbak <marius@kotsbak.com>
Cc: stable <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>