mISDN: fix possible use-after-free in HFC_cleanup()
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 v5.10.51 by commit b7ee9ae1e0cf55a037c4a99af2acc5d78cb7802d. For more details please see the references link.