iouring: Fix a null-ptr-deref in iotctxexitcb()
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 v6.0.13 by commit d91edca1943453aaaba4f380f6f364346222e5cf, it was introduced in version v5.12 by commit d56d938b4bef3e1421a42023cdcd6e13c1f50831. For more details please see the references link.