Input: adxl34x - make platform_data include self contained

Since it suggests to use defines from input.h (ABS_X, ...), also include
the file to make them available.
Signed-off-by: Wolfram Sang <w.sang@pengutronix.de>
Acked-by: Michael Hennerich <michael.hennerich@analog.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

include/linux/input/adxl34x.h

@@ -13,6 +13,8 @@
 #ifndef __LINUX_INPUT_ADXL34X_H__
 #define __LINUX_INPUT_ADXL34X_H__
 
+#include <linux/input.h>
+
 struct adxl34x_platform_data {
 
 	/*