drm/amd/powerplay: Disable gfx CGPG when suspend smu

if no disable gfx CGPG when suspend smu, enabling gfx CGPG will fail when resume smu.

Platform: Renoir
dmesg log information:

[  151.844110 ] amdgpu: [powerplay] SMU is resuming...
[  151.844116 ] amdgpu: [powerplay] dpm has been disabled
[  151.844604 ] amdgpu: [powerplay] Failed to send message 0x2f,response 0xfffffffb param 0x1
[  151.844605 ] amdgpu: [powerplay] SMU is resumed successfully!

Signed-off-by: chen gong <curry.gong@amd.com>
Acked-by: Evan Quan <evan.quan@amd.com>
Reviewed-by: Huang Rui <ray.huang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>