staging: comedi: das800: Fix endian problem for AI command data

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: ad9eb43c ("staging: comedi: das800: use comedi_buf_write_samples()")
Cc: <stable@vger.kernel.org> # 3.19+
Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Link: https://lore.kernel.org/r/20210223143055.257402-6-abbotti@mev.co.ukSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/comedi/drivers/das800.c

@@ -427,7 +427,7 @@ static irqreturn_t das800_interrupt(int irq, void *d)
 	struct comedi_cmd *cmd;
 	unsigned long irq_flags;
 	unsigned int status;
-	unsigned int val;
+	unsigned short val;
 	bool fifo_empty;
 	bool fifo_overflow;
 	int i;