drm/amdgpu: Correct the amdgpu_ucode_fini_bo place for Tonga

The amdgpu_ucode_fini_bo should be called after gfx_v8_0_hw_fini,
or it will have KCQ disable failed issue.

For Tonga, as it firstly finishes SMC block, and the SMC hw fini
will call amdgpu_ucode_fini, which will lead the amdgpu_ucode_fini_bo
called before gfx_v8_0_hw_fini, this is incorrect.

Signed-off-by: Emily Deng <Emily.Deng@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>