CVE-2026-98780: drm/amdgpu: fix IP instance memory leak on kobject add failure

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

drm/amdgpu: fix IP instance memory leak on kobject add failure

amdgpudiscoverysysfsips() allocates iphwinstance with kzallocflex() and initializes its embedded kobject before calling kobjectadd().

If kobjectadd() fails, the return value is ignored and execution continues without dropping the initial kobject reference. The failed kobject is not retained in the kset list, so the normal sysfs teardown path cannot find it. As a result, iphwinstancerelease() is never called and the iphwinstance allocation is leaked.

Call kobjectput() when kobjectadd() fails so the initial reference is dropped and iphwinstancerelease() can free the allocation. Keep the existing best-effort sysfs behavior by continuing with the remaining IP entries after the failed registration.

The issue was identified by a static analysis tool I developed and confirmed by manual review.

(cherry picked from commit 5c75fbcca8af1096d8d9415b91d8ea6212c22ee1)