drivers/staging/comedi/drivers/das16.c: needs slab.h

alpha allmodconfig:

drivers/staging/comedi/drivers/das16.c: In function 'das16_detach':
drivers/staging/comedi/drivers/das16.c🔢 error: implicit declaration of function 'kfree'

Cc: Ian Abbott <abbotti@mev.co.uk>
Reviewed-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/comedi/drivers/das16.c

@@ -81,6 +81,7 @@
  */
 
 #include <linux/module.h>
+#include <linux/slab.h>
 #include <linux/delay.h>
 #include <linux/pci.h>
 #include <linux/interrupt.h>