leds: max8997: Remove unneeded workqueue include

Work queues are not used in this driver, so remove the include.
Signed-off-by: Andrew Lunn <andrew@lunn.ch>

drivers/leds/leds-max8997.c

@@ -13,7 +13,6 @@
 #include <linux/module.h>
 #include <linux/err.h>
 #include <linux/slab.h>
-#include <linux/workqueue.h>
 #include <linux/leds.h>
 #include <linux/mfd/max8997.h>
 #include <linux/mfd/max8997-private.h>