staging: comedi: 8255: sample types are unsigned

Sample values in comedi are generally represented as unsigned values.
`subdev_8255_interrupt()` calls `comedi_buf_put()` with a `short` data
value merely because that's what was previously expected.  Since it now
expects an `unsigned short`, change it here for consistency.
Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/comedi/drivers/8255.c

@@ -112,7 +112,7 @@ void subdev_8255_interrupt(struct comedi_device *dev,
 {
 	struct subdev_8255_private *spriv = s->private;
 	unsigned long iobase = spriv->iobase;
-	short d;
+	unsigned short d;
 
 	d = spriv->io(0, _8255_DATA, 0, iobase);
 	d |= (spriv->io(0, _8255_DATA + 1, 0, iobase) << 8);