rtc: isl12057: make of_device_id array const

Make of_device_id array const, because all OF functions handle it as
const.

Signed-off-by: Jingoo Han <jg1.han@samsung.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/rtc/rtc-isl12057.c

@@ -278,7 +278,7 @@ static int isl12057_probe(struct i2c_client *client,
 }
 
 #ifdef CONFIG_OF
-static struct of_device_id isl12057_dt_match[] = {
+static const struct of_device_id isl12057_dt_match[] = {
 	{ .compatible = "isl,isl12057" },
 	{ },
 };