CVE-2026-46079 rbd: fix null-ptr-deref when device_add_disk() fails

In the Linux kernel, the following vulnerability has been resolved: rbd: fix null-ptr-deref when deviceadddisk fails dorbdadd publishes the device with deviceadd before calling deviceadddisk. If deviceadddisk fails after deviceadd succeeds, the error path calls rbdfreedisk directly and then later...