drm/amd/display: add KUnit tests for DM stream scaling

[WHAT]
Add KUnit tests for the stream scaling path: a disable-underscan case
for is_scaling_state_different, and coverage of
amdgpu_dm_update_stream_scaling_settings across the full-screen
default, RMX_FULL, RMX_ASPECT pillarbox/letterbox, RMX_CENTER and
underscan paths.

Assisted-by: Copilot:Claude-Opus-4.8
Reviewed-by: Bhawanpreet Lakha <bhawanpreet.lakha@amd.com>
Signed-off-by: Alex Hung <alex.hung@amd.com>
Signed-off-by: Wayne Lin <wayne.lin@amd.com>
Tested-by: Dan Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

0 files changed, 0 insertions, 0 deletions