mtd: Missing slab.h include

Signed-off-by: NDavid S. Miller <davem@davemloft.net>
Signed-off-by: NArtem Bityutskiy <Artem.Bityutskiy@nokia.com>
Signed-off-by: NDavid Woodhouse <David.Woodhouse@intel.com>

drivers/mtd/nand/denali.c

@@ -21,6 +21,7 @@
 #include <linux/delay.h>
 #include <linux/wait.h>
 #include <linux/mutex.h>
+#include <linux/slab.h>
 #include <linux/pci.h>
 #include <linux/mtd/mtd.h>
 #include <linux/module.h>