drm/amdgpu: fix mmhub client id out-of-bounds access

Properly handle cid 0x140.

Fixes: aba2be41 ("drm/amdgpu: add mmhub 3.3.0 support")
Signed-off-by: Lang Yu <Lang.Yu@amd.com>
Reviewed-by: Yifan Zhang <yifan1.zhang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>