drivers/leds: Add module.h to files using it implicitly

A pending cleanup will mean that module.h won't be implicitly
everywhere anymore.  Make sure the modular drivers in the leds
dir are actually calling out for <module.h> explicitly in advance.

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
diff --git a/drivers/leds/leds-gpio.c b/drivers/leds/leds-gpio.c
index 3d8bc32..2ba756b 100644
--- a/drivers/leds/leds-gpio.c
+++ b/drivers/leds/leds-gpio.c
@@ -18,6 +18,7 @@
 #include <linux/of_gpio.h>
 #include <linux/slab.h>
 #include <linux/workqueue.h>
+#include <linux/module.h>
 
 #include <asm/gpio.h>