iio: accel: kxcjk-1013: only set power state if CONFIG_PM is defined
When CONFIG_PM is not defined and the driver tries to power off the device,
kxcjk1013_set_power_state will call pm_runtime_put_autosuspend, which is
not implemented (wil return -ENOSYS).
Only call pm_runtime calls to change power state when CONFIG_PM is defined.