iio: cros_ec_accel_legacy: Use cros_ec_sensors_core

Remove duplicate code in cros-ec-accel-legacy,
use cros-ec-sensors-core functions and structures when possible.

On glimmer, check the 2 accelerometers are presented and working.
Signed-off-by: Gwendal Grignou <gwendal@chromium.org>
Reviewed-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/accel/Kconfig

@@ -202,9 +202,7 @@ config HID_SENSOR_ACCEL_3D
 
 config IIO_CROS_EC_ACCEL_LEGACY
 	tristate "ChromeOS EC Legacy Accelerometer Sensor"
-	select IIO_BUFFER
-	select IIO_TRIGGERED_BUFFER
-	select CROS_EC_LPC_REGISTER_DEVICE
+	depends on IIO_CROS_EC_SENSORS_CORE
 	help
 	  Say yes here to get support for accelerometers on Chromebook using
 	  legacy EC firmware.