usb: misc: iowarrior: fix information leak to userland

Structure iowarrior_info is copied to userland with padding byted
between "serial" and "revision" fields uninitialized.  It leads to
leaking of contents of kernel stack memory.

Signed-off-by: Vasiliy Kulikov <segooon@gmail.com>
Cc: stable <stable@kernel.org>
Acked-by: Kees Cook <kees.cook@canonical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>