staging: comedi: das6402: Fix endian problem for AI command data

commit 1c0f20b upstream.

The analog input subdevice supports Comedi asynchronous commands that
use Comedi's 16-bit sample format.  However, the call to
`comedi_buf_write_samples()` is passing the address of a 32-bit integer
variable.  On bigendian machines, this will copy 2 bytes from the wrong
end of the 32-bit value.  Fix it by changing the type of the variable
holding the sample value to `unsigned short`.

Fixes: d1d24cb ("staging: comedi: das6402: read analog input samples in interrupt handler")
Cc: <stable@vger.kernel.org> # 3.19+
Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Link: https://lore.kernel.org/r/20210223143055.257402-5-abbotti@mev.co.uk
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/comedi/drivers/das6402.c

@@ -186,7 +186,7 @@ static irqreturn_t das6402_interrupt(int irq, void *d)
 	if (status & DAS6402_STATUS_FFULL) {
 		async->events |= COMEDI_CB_OVERFLOW;
 	} else if (status & DAS6402_STATUS_FFNE) {
-		unsigned int val;
+		unsigned short val;
 
 		val = das6402_ai_read_sample(dev, s);
 		comedi_buf_write_samples(s, &val, 1);