iio: cros_ec: Set Gyroscope default frequency to 25Hz

BMI160 Minimium gyroscope frequency in normal mode is 25Hz.
When older EC firmware do not report their sensors frequencies,
use 25Hz as the minimum for gyroscope to be sure it works on BMI160.

Fixes: ae7b02ad ("iio: common: cros_ec_sensors: Expose cros_ec_sensors frequency range via iio sysfs")
Signed-off-by: Gwendal Grignou <gwendal@chromium.org>
Reviewed-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Cc: <Stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>