Staging: comedi: das6402.c: Checkpatch cleanup

ERROR: Macros with complex values should be enclosed in parenthesis
+#define N_WORDS 3000*64
Signed-off-by: Andrea Gelmini <andrea.gelmini@gelma.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/staging/comedi/drivers/das6402.c

@@ -45,7 +45,7 @@ This driver has suffered bitrot.
 
 #define DAS6402_SIZE 16
 
-#define N_WORDS 3000*64
+#define N_WORDS (3000*64)
 
 #define STOP    0
 #define START   1