drm/radeon: fix a possible null pointer dereference
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 v5.15.47 by commit 7b7fba107b2c4ec7673d0f45bdbb9d1af697d9b9. For more details please see the references link.