rtc: at91sam9: remove useless include

Definitions from linux/platform_data/atmel.h are not used, remove the
include.
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>

drivers/rtc/rtc-at91sam9.c

@@ -19,7 +19,6 @@
 #include <linux/mfd/syscon.h>
 #include <linux/module.h>
 #include <linux/of.h>
-#include <linux/platform_data/atmel.h>
 #include <linux/platform_device.h>
 #include <linux/regmap.h>
 #include <linux/rtc.h>