rtc: ab8500: Constify platform_device_id

The platform_device_id is not modified by the driver and core uses it as
const.

Signed-off-by: Krzysztof Kozlowski <k.kozlowski.k@gmail.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>

drivers/rtc/rtc-ab8500.c

@@ -442,7 +442,7 @@ static const struct rtc_class_ops ab8540_rtc_ops = {
 	.alarm_irq_enable	= ab8500_rtc_irq_enable,
 };
 
-static struct platform_device_id ab85xx_rtc_ids[] = {
+static const struct platform_device_id ab85xx_rtc_ids[] = {
 	{ "ab8500-rtc", (kernel_ulong_t)&ab8500_rtc_ops, },
 	{ "ab8540-rtc", (kernel_ulong_t)&ab8540_rtc_ops, },
 };