drm/amd/display: Populate dcn2.1 bounding box before state duplication

[Why]
If system is overclocked, only 1 bounding box state will
be sent by SMU. This results in an empty state being copied
for DML calculations causing black screens and corruption.

[How]
Fully populate bounding box before duplicating last state.

Signed-off-by: Sung Lee <sung.lee@amd.com>
Reviewed-by: Tony Cheng <Tony.Cheng@amd.com>
Acked-by: Qingqing Zhuo <Qingqing.Zhuo@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>