iio: trigger: sysfs: fix use-after-free on remove

iio: trigger: sysfs: fix use-after-free on remove

This is an automated ID intended to aid in discovery of potential security vulnerabilities. The actual impact and attack plausibility have not yet been proven.
This ID is fixed in Linux Kernel version v4.9.321 by commit d6111e7bdb8ec27eb43d01c4cd4ff1620a75f7f2, it was introduced in version v3.7 by commit f38bc926d022ebd67baad6ac7fc22c95fbc6238c. For more details please see the references link.