staging: comedi: dt282x: dt282x_ai_insn_read() always fails

In dt282x_ai_insn_read() we call this macro like:
wait_for(!mux_busy(), comedi_error(dev, "timeout\n"); return -ETIME;);
Because the if statement doesn't have curly braces it means we always
return -ETIME and the function never succeeds.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Ian Abbott <abbotti@mev.co.uk>
Cc: stable <stable@vger.kernel.org> # 2.6.36+
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/comedi/drivers/dt282x.c

@@ -267,8 +267,9 @@ struct dt282x_private {
 			}					\
 			udelay(5);				\
 		}						\
-		if (_i)						\
+		if (_i) {					\
 			b					\
+		}						\
 	} while (0)
 
 static int prep_ai_dma(struct comedi_device *dev, int chan, int size);