staging: comedi: fix infoleak to userspace

driver_name and board_name are pointers to strings, not buffers of size
COMEDI_NAMELEN.  Copying COMEDI_NAMELEN bytes of a string containing
less than COMEDI_NAMELEN-1 bytes would leak some unrelated bytes.

Signed-off-by: Vasiliy Kulikov <segoon@openwall.com>
Cc: stable <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
static void comedi_device_init(struct comedi_device *dev)
{
	memset(dev, 0, sizeof(struct comedi_device));
	spin_lock_init(&dev->spinlock);
	mutex_init(&dev->mutex);
	dev->minor = -1;
}

static void comedi_device_init(struct comedi_device *dev)
{
	memset(dev, 0, sizeof(struct comedi_device));
	spin_lock_init(&dev->spinlock);
	mutex_init(&dev->mutex);
	dev->minor = -1;
}
