!8410 iio: adc: stm32-adc: harden against NULL pointer deref in stm32_adc_probe()

Merge Pull Request from: @ci-robot 
 
PR sync from: Cai Xinchen <caixinchen1@huawei.com>
https://mailweb.openeuler.org/hyperkitty/list/kernel@openeuler.org/message/PEQSADGTYECPYP6WUWDYD44NOKGPAN6D/ 
 
https://gitee.com/src-openeuler/kernel/issues/I9REBR 
 
Link:https://gitee.com/openeuler/kernel/pulls/8410

 

Reviewed-by: Liu YongQiang <liuyongqiang13@huawei.com>
Signed-off-by: Zhang Changzhong <zhangchangzhong@huawei.com>