drm/amd/display: Add vblank handling tests for crtc

Add KUnit coverage for the CRTC vblank paths:

- amdgpu_dm_crtc_handle_vblank: no-event completion and the
  AMDGPU_FLIP_SUBMITTED guard that keeps a pending event pending.
- amdgpu_dm_crtc_vblank_control_worker: enable increments, disable
  decrements, and disable clamps the active vblank IRQ count at zero.
- amdgpu_dm_crtc_disable_vblank: disable path returns cleanly when the
  IRQ subsystem is not installed.

Expose amdgpu_dm_crtc_vblank_control_worker for KUnit via
STATIC_IFN_KUNIT/EXPORT_IF_KUNIT and declare it in the header.

Assisted-by: Copilot:Claude-Opus-4.8
Reviewed-by: Alex Hung <alex.hung@amd.com>
Signed-off-by: Bhawanpreet Lakha <bhawanpreet.lakha@amd.com>
Signed-off-by: Roman Li <roman.li@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