drm/amdgpu: add support for new smc firmware on tonga

Newer tonga parts require new smc firmware.

Reviewed-by: Huang Rui <ray.huang@amd.com>
Reviewed-by: Eric Huang <JinHuiEric.Huang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org