drm/amd/display: Unify optimize_required flags and VRR adjustments

[why]
There is only a single call to dc_post_update_surfaces_to_stream so
there is no need to have two flags to control it. Unifying this to a
single flag allows dc_stream_adjust_vmin_vmax to skip actual
programming when there is no change required.

[how]
Remove wm_optimze_required flag and set only optimize_required in its
place. Then in dc_stream_adjust_vmin_vmax, check that the stream timing
range matches the requested one and skip programming if they are equal.

Reviewed-by: Jun Lei <jun.lei@amd.com>
Acked-by: Wayne Lin <wayne.lin@amd.com>
Signed-off-by: Aric Cyr <aric.cyr@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>