staging: comedi: remove duplicated include from ni_pcimio.c

Remove duplicated include.
Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/comedi/drivers/ni_pcimio.c

@@ -110,7 +110,6 @@ SCXI is probably broken for m-series boards.
 
 */
 
-#include <linux/delay.h>
 #include <linux/delay.h>
 
 #include "../comedidev.h"