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 v5.4.230 by commit ffef77794fb5f1245c3249b86342bad2299accb5, it was introduced in version v3.0 by commit 74c5b31c6618f01079212332b2e5f6c42f2d6307. For more details please see the references link.