drm/amd/display: Perform plane updates only when needed

[Why]
Our old logic: if pageflip, update freesync and plane address.
Otherwise, update everything.
This over-updated on non-pageflip cases, and it failed to
update if pageflip and non-pageflip changes occurred on
the same commit

[How]
Update flip_addrs on pageflips.
Update scaling_info when it changes.
Update color fields on color changes.
Updates plane_info always because we don't have a good way of
knowing when it needs to be updated.

Unfortunately, this means that every stream commit involves two
calls into DC.  In particular, on pageflips there is a second,
pointless update that changes nothing but costs several
microseconds (about a 50% increase in time taken). The update is
fast, but there are comparisons and some useless programming.

Leave TODOs indicating dissatisfaction.

Signed-off-by: David Francis <David.Francis@amd.com>
Reviewed-by: Harry Wentland <Harry.Wentland@amd.com>
Reviewed-by: Nicholas Kazlauskas <Nicholas.Kazlauskas@amd.com>
Acked-by: Leo Li <sunpeng.li@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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