mfd: Missing slab.h includes

Signed-off-by: NDavid S. Miller <davem@davemloft.net>
Signed-off-by: NSamuel Ortiz <sameo@linux.intel.com>

drivers/mfd/janz-cmodio.c

@@ -18,6 +18,7 @@
 #include <linux/interrupt.h>
 #include <linux/delay.h>
 #include <linux/platform_device.h>
+#include <linux/slab.h>
 #include <linux/mfd/core.h>
 
 #include <linux/mfd/janz.h>