drm/tests: hdmi: Handle drm_kunit_helper_enable_crtc_connector() returning EDEADLK

drm/tests: hdmi: Handle drm_kunit_helper_enable_crtc_connector() returning EDEADLK

Fedora/CentOS/RHEL CI is reporting intermittent failures while running
the KUnit tests present in drm_hdmi_state_helper_test.c [1].

While the specific test causing the failure change between runs, all of
them are caused by drm_kunit_helper_enable_crtc_connector() returning
-EDEADLK. The error trace always follow this structure:

    # <test name>: ASSERTION FAILED at
    # drivers/gpu/drm/tests/drm_hdmi_state_helper_test.c:<line>
    Expected ret == 0, but
        ret == -35 (0xffffffffffffffdd)

As documented, if the drm_kunit_helper_enable_crtc_connector() function
returns -EDEADLK (-35), the entire atomic sequence must be restarted.

Handle this error code for all function calls.

Closes: https://datawarehouse.cki-project.org/issue/4039  [1]
Fixes: 6a5c0ad7e08e ("drm/tests: hdmi_state_helpers: Switch to new helper")
Reviewed-by: Maxime Ripard <mripard@kernel.org>
Signed-off-by: José Expósito <jose.exposito89@gmail.com>
Link: https://patch.msgid.link/20251104102258.10026-1-jose.exposito89@gmail.com