drivers/input: Add module.h to modular drivers implicitly using it

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

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
diff --git a/drivers/input/touchscreen/ad7879.c b/drivers/input/touchscreen/ad7879.c
index 131f9d1c..3b2e9ed 100644
--- a/drivers/input/touchscreen/ad7879.c
+++ b/drivers/input/touchscreen/ad7879.c
@@ -33,6 +33,7 @@
 #include <linux/gpio.h>
 
 #include <linux/spi/ad7879.h>
+#include <linux/module.h>
 #include "ad7879.h"
 
 #define AD7879_REG_ZEROS		0