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

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.

Fixes: 9a9a369d6178 ("iio: accel: kxsd9: Deploy system and runtime PM")
Signed-off-by: Biren Pandya <birenpandya@gmail.com>
Assisted-by: Claude:claude-opus-4-8 coccinelle
Cc: <Stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>