drm/amd/powerplay: add Fiji SMU support.

Add support for the SMU manager for Fiji. This handles the
firmware loading for other IP blocks (GFX, SDMA, etc.).

Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Eric Huang <JinHuiEric.Huang@amd.com>