drm/amdgpu: introduce vmhub definition for multi-partition cases (v3)

v1: Each partition has its own gfxhub or mmhub. adjust
the num of MAX_VMHUBS and the GFXHUB/MMHUB layout (Le)

v2: re-design the AMDGPU_GFXHUB/AMDGPU_MMHUB layout (Le)

v3: apply the gfxhub/mmhub layout to new IPs (Hawking)

v4: fix up gmc11 (Alex)

v5: rebase (Alex)

Signed-off-by: Le Ma <le.ma@amd.com>
Acked-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Hawking Zhang <Hawking.Zhang@amd.com>
Signed-off-by: Hawking Zhang <Hawking.Zhang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>