drm/amd/display: Add KUnit tests for mst_types

Add KUnit coverage for the following MST functions:

- dm_dp_aux_transfer(): native read/write, partial write, error
  result remapping, and HPD disconnect quirk via fake DC link service
- dm_dp_aux_transfer_result(): error code translation
- dm_dp_aux_fill_payload_flags(): request flag decoding
- dm_mst_msg_ready_mask(): ESI mask selection
- dm_mst_select_esi_dpcd(): DPCD address/length selection
- dm_mst_atomic_best_encoder(): encoder selection by CRTC ID
- dm_dp_mst_detect(): unregistered connector early return
- dm_dp_mst_atomic_check(): no-old-CRTC early return
- dm_dp_create_fake_mst_encoders(): encoder init and CRTC mask
- dm_handle_mst_sideband_msg_ready_event(): idle no-ready-bits
- retrieve_branch_specific_data(): branch OUI parsing
- retrieve_downstream_port_device(): downstream port present
- needs_dsc_aux_workaround(): DSC workaround matching
- dm_mst_get_pbn_divider(): null link guard
- amdgpu_dm_mst_reset_mst_connector_setting(): field reset
- dm_dp_mst_is_port_support_mode(): FP-off fallback

Assisted-by: Copilot:GPT-5.5
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>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

0 files changed, 0 insertions, 0 deletions