drm/amdgpu: Add FGCG logic for GFX v9.4.3

Add logic for fine grain clock gating logic for GFX v9.4.3. The feature
will be controlled using CG flags. Also, make a change so that RLC safe
mode entry/exit is done only once during CG update sequence.

Signed-off-by: Lijo Lazar <lijo.lazar@amd.com>
Reviewed-by: Hawking Zhang <Hawking.Zhang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>