mfd: max14577: Include missing err.h

Add this header explicitly for IS_ERR and friends.
Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

drivers/mfd/max14577.c

@@ -18,6 +18,7 @@
  * This driver is based on max8997.c
  */
 
+#include <linux/err.h>
 #include <linux/module.h>
 #include <linux/interrupt.h>
 #include <linux/mfd/core.h>