CVE-2026-72272: fbdev: radeon: fix potential memory leak in radeonfb_pci_register()

In the Linux kernel, the following vulnerability has been resolved:

fbdev: radeon: fix potential memory leak in radeonfbpciregister()

The function radeonfbpciregister() allocates memory for modelist (by calling radeoncheckmodes() which calls fbaddvideomode()). The memory is appended to info->modelist, but is not freed in subsequent error paths. Fix this by calling fbdestroymodelist().