iio: adc: ina2xx: Avoid double reference counting from get_task_struct/put_task_struct()

kthread_run() and kthread_stop() already do reference
counting of the task, so remove get_task_struct/put_task_struct()
to avoid double reference counting.

Signed-off-by: Cai Huoqing <caihuoqing@baidu.com>
Link: https://lore.kernel.org/r/20211021124254.3247-2-caihuoqing@baidu.com


Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>