drm/amdgpu: cleanup useless smu_ucode_xfer_vi.h

This header won't be used at amdgpu, it moved to powerplay.

Signed-off-by: Huang Rui <ray.huang@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>