drm/amd/powerplay: implement sensor of get feature mask

drm/amd/powerplay: implement sensor of get feature mask

add sensor interface of feature mask for debugfs.
this interface is not ip related function, so need move high level
file to implement (amdgpu_smu)

Signed-off-by: Kevin Wang <Kevin1.Wang@amd.com>
Reviewed-by: Huang Rui <ray.huang@amd.com>
Reviewed-by: Evan Quan <evan.quan@amd.com>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>