drm/amdkfd: Extend CU mask to 8 SEs (v3)

Following bitmap layout logic introduced by:
"drm/amdgpu: support get_cu_info for Arcturus".

v2: squash in fixup for gfx_v9_0.c (Alex)
v3: squash in debug print output fix

Signed-off-by: Jay Cornwall <Jay.Cornwall@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>