drm/amd/display: Optimize clocks on clock change

[WHY]
Presently, there is no way for clocks to be lowered, only raised.

[HOW]
Compare clock status against previous known clock status, and optimize
if different.
This requires re-ordering the layout of the dc_clocks structure, as the
current ordering allows identical clock states to appear different.

Signed-off-by: Wesley Chalmers <Wesley.Chalmers@amd.com>
Reviewed-by: Aric Cyr <Aric.Cyr@amd.com>
Acked-by: Anthony Koo <Anthony.Koo@amd.com>
Acked-by: Leo Li <sunpeng.li@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>