drm/amdgpu: fix GFX10 missing CSIB set(v3)

still need to init csb even for SRIOV

v2:
drop init_pg() for gfx10 at all since
PG and GFX off feature will be fully controled
by RLC and SMU fw for gfx10

v3:
drop the flush_gpu_tlb lines since we consider
it is only usefull in emulation

Signed-off-by: Monk Liu <Monk.Liu@amd.com>
Reviewed-by: Hawking Zhang <Hawking.Zhang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>