iio: accel: kionix-kx022a: Use correct header(s) instead of string_helpers.h

There is nothing from string_helpers.h used in the driver, correct
the header inclusion block accordingly.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Matti Vaittinen <mazziesaccount@gmail.com>
Link: https://lore.kernel.org/r/20230808164204.66818-1-andriy.shevchenko@linux.intel.comSigned-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/accel/kionix-kx022a.c

@@ -15,7 +15,7 @@
 #include <linux/regmap.h>
 #include <linux/regulator/consumer.h>
 #include <linux/slab.h>
-#include <linux/string_helpers.h>
+#include <linux/string_choices.h>
 #include <linux/units.h>
 
 #include <linux/iio/iio.h>