radeon and intel use the exact same definition.
Reviewed-by: NAlex Deucher <alexander.deucher@amd.com>
Acked-by: NDave Airlie <airlied@gmail.com>

v2: Kill 2 more helpers in intel_dp.c that I've missed.
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>