tty: synclinkgt: Fix null-pointer-dereference in slgtclean()
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 v5.18.4 by commit 1ceb4ca9543a8a788febf6bc8dad2e605e172d5e. For more details please see the references link.