drm/amd/display: Test unassigned OTG CRTC lookup

[WHAT]
amdgpu_dm_get_crtc_by_otg_inst() had no test for an OTG instance
of -1, so its WARN_ON guard and the fallback to the first CRTC were
never executed.

[HOW]
Add dm_test_get_crtc_by_otg_inst_unassigned_otg(), which installs
a CRTC as mode_info.crtcs[0] and asserts the lookup returns it rather
than walking the CRTC list.

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