iio: common: hid-sensor-attributes: make unit_conversion const

Add const qualifier to struct unit_conversion[]. This is read-only data
so it can be made const.

Signed-off-by: David Lechner <dlechner@baylibre.com>
Link: https://patch.msgid.link/20250628-iio-const-data-14-v1-1-4faa8015e122@baylibre.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

Author: dlech

drivers/iio/common/hid-sensors/hid-sensor-attributes.c

@@ -11,7 +11,7 @@
 #include <linux/hid-sensor-hub.h>
 #include <linux/iio/iio.h>
 
-static struct {
+static const struct {
 	u32 usage_id;
 	int unit; /* 0 for default others from HID sensor spec */
 	int scale_val0; /* scale, whole number */