thermal/qcom/tsens-common : fix possible object reference leak

of_find_device_by_node() takes a reference to the struct device
when it finds a match via get_device.
We also should make sure to drop the reference to the device
taken by of_find_device_by_node() when returning error.

Signed-off-by: Peng Hao <peng.hao2@zte.com.cn>
Signed-off-by: Eduardo Valentin <edubezval@gmail.com>