drm/tests: Handle EDEADLK in drm_test_check_valid_clones()

drm/tests: Handle EDEADLK in drm_test_check_valid_clones()

Fedora/CentOS/RHEL CI is reporting intermittent failures while running
the drm_test_check_valid_clones() KUnit test.

The error log can be either [1]:

    # drm_test_check_valid_clones: ASSERTION FAILED at
    # drivers/gpu/drm/tests/drm_atomic_state_test.c:295
    Expected ret == param->expected_result, but
        ret == -35 (0xffffffffffffffdd)
        param->expected_result == 0 (0x0)

Or [2] depending on the test case:

    # drm_test_check_valid_clones: ASSERTION FAILED at
    # drivers/gpu/drm/tests/drm_atomic_state_test.c:295
    Expected ret == param->expected_result, but
        ret == -35 (0xffffffffffffffdd)
        param->expected_result == -22 (0xffffffffffffffea)

Restart the atomic sequence when EDEADLK is returned.

[1] https://s3.amazonaws.com/arr-cki-prod-trusted-artifacts/trusted-artifacts/2113057246/test_x86_64/11802139999/artifacts/jobwatch/logs/recipes/19824965/tasks/204347800/results/946112713/logs/dmesg.log
[2] https://s3.amazonaws.com/arr-cki-prod-trusted-artifacts/trusted-artifacts/2106744297/test_aarch64/11762450907/artifacts/jobwatch/logs/recipes/19797942/tasks/204139727/results/945094561/logs/dmesg.log

Fixes: 88849f24e2ab ("drm/tests: Add test for drm_atomic_helper_check_modeset()")
Closes: https://datawarehouse.cki-project.org/issue/4004
Reviewed-by: Maxime Ripard <mripard@kernel.org>
Signed-off-by: José Expósito <jose.exposito89@gmail.com>
Link: https://patch.msgid.link/20251104102535.12212-1-jose.exposito89@gmail.com