drm/amdgpu: fix UVD suspend and resume for VI APU

User space passed the same handle before suspend and after resume,
so we have remove the session and handle destroy, and keep the
firmware untouched.

Signed-off-by: Leo Liu <leo.liu@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Cc: stable@vger.kernel.org