iio: accel: kxsd9: fix runtime PM imbalance on write_raw() error

In the Linux kernel, the following vulnerability has been resolved: iio: accel: kxsd9: fix runtime PM imbalance on write_raw() error kxsd9_write_raw() takes a runtime PM reference with pm_runtime_get_sync() but returns -EINVAL directly when a scale with a non-zero integer part is requested, skipping the matching pm_runtime_put_autosuspend(). This leaks a runtime PM usage-counter reference on every such write, after which the device can no longer autosuspend. Set the error code and fall through to the existing put instead of returning early.