kernel: drm/amdkfd: amdkfd_free_gtt_mem clear the correct pointer

In the Linux kernel, the following vulnerability has been resolved: drm/amdkfd: amdkfdfreegttmem clear the correct pointer Pass pointer reference to amdgpubounref to clear the correct pointer, otherwise amdgpubounref clear the local variable, the original pointer not set to NULL, this could cause...