drm/amdgpu: add MGCG perfmon setting for gfx11

Enable GFX11 MGCG perfmon setting.
V2: set rlc to saft mode before setting.

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