Draft: test/amdgpu: Add emit mem sync flag for test IB

In syncobj test, 3 threads will be created. Sometimes the first gfx IB and the third sdma IB will use same physical page. There will be risk that sdma engine will read gfx IB in the same physical page. So better to flush the cache before commit sdma IB.

driver update: https://lists.freedesktop.org/archives/amd-gfx/2021-April/061940.html

Signed-off-by: Jinzhou Su Jinzhou.Su@amd.com

Reviewed-by: Huang Rui ray.huang@amd.com

Acked-by: Alex Deucher alexander.deucher@amd.com