gsmi: fix null-deref in gsmigetvariable
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 v5.15.90 by commit eb0421d90f916dffe96b4c049ddf01c0c50620d2, it was introduced in version v3.0 by commit 74c5b31c6618f01079212332b2e5f6c42f2d6307. For more details please see the references link.