drm/amd/display: Add clock info struct

Signed-off-by: Corbin McElhanney <corbin.mcelhanney@amd.com>
Reviewed-by: Logatharshan Thothiralingam <Logatharshan.Thothiralingam@amd.com>
Acked-by: Harry Wentland <Harry.Wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>