mfd: Constify aat2870-core i2c_device_id table

Signed-off-by: Axel Lin <axel.lin@gmail.com>
diff --git a/drivers/mfd/aat2870-core.c b/drivers/mfd/aat2870-core.c
index 7620617..e6da563 100644
--- a/drivers/mfd/aat2870-core.c
+++ b/drivers/mfd/aat2870-core.c
@@ -500,7 +500,7 @@
 #define aat2870_i2c_resume	NULL
 #endif /* CONFIG_PM */
 
-static struct i2c_device_id aat2870_i2c_id_table[] = {
+static const struct i2c_device_id aat2870_i2c_id_table[] = {
 	{ "aat2870", 0 },
 	{ }
 };