drm/amdgpu: Modify indirect register access for amdkfd_gfx_v9 sriov

Modify GC register access from MMIO to RLCG if the indirect
flag is set

Signed-off-by: Victor Skvortsov <victor.skvortsov@amd.com>
Reviewed-by: David Nieto <david.nieto@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>