tty: ngsm: add sanity check for gsm->receive in gsmreceive_buf()
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 v5.15.66 by commit 309aea4b6b813f6678c3a547cfd7fe3a76ffa976, it was introduced in version v5.15.61 by commit dfa9b6d34aac2154b5e926d7a7a061123bf137c6. For more details please see the references link.