drm/amd/display: Fold modifier append tests

[WHAT]
Reduce the four KUnit tests for amdgpu_dm_plane_add_modifier() to two,
and the two tests for amdgpu_dm_plane_add_modifier_dedup() to one.

[HOW]
Group the append and capacity-growth cases into one test and the
NULL-list and allocation-failure cases into another, and run the
duplicate-skip and NULL-list dedup cases in sequence within a single
test.

Assisted-by: Copilot:Claude-Opus-5
Reviewed-by: Bhawanpreet Lakha <bhawanpreet.lakha@amd.com>
Signed-off-by: Alex Hung <alex.hung@amd.com>
Signed-off-by: George Zhang <george.zhang@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