mISDN: fix possible memory leak in mISDNregisterdevice()
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 v5.4.224 by commit 2ff6b669523d3b3d253a044fa9636a67d0694995, it was introduced in version v2.6.30 by commit 1fa5ae857bb14f6046205171d98506d8112dd74e. For more details please see the references link.