tests/amdgpu: add deadlock test for sdma

deadlock test for sdma will cause gpu recoverty.
disable the test for now until GPU reset recovery could survive at least
1000 times test.

v2: add modprobe parameter

Reviewed-and-tested-by: Evan Quan <evan.quan@amd.com>
Acked-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Flora Cui <flora.cui@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>