drm/amdgpu: Destroy psp ring in hw_fini

Fix issue that PSP initialization will fail if reload amdgpu module.
That's because the PSP ring must be destroyed to be ready for the
next time PSP initialization.

Changes in v2:
	- Move psp_ring_destroy before all BOs free (suggested by
	  Ray Huang).
Changes in v3:
	- Check firmware load type, if it is not PSP, we should do
	  nothing in fw_fini(), and of course will not destroy
	  PSP ring too (suggested by Ray Huang).

Signed-off-by: Trigger Huang <trigger.huang@amd.com>
Reviewed-by: Xiangliang Yu <Xiangliang.Yu@amd.com>
Reviewed-by: Huang Rui <ray.huang@amd.com>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>