CVE-2021-47144

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

drm/amd/amdgpu: fix refcount leak

[Why]
the gem object rfb->base.obj[0] is get according to num_planes
in amdgpufb_create, but is not put according to num_planes

[How]
put rfb->base.obj[0] in amdgpu_fbdev_destroy according to num_planes