amdgpu: add the interface of waiting multiple fences

Signed-off-by: Junwei Zhang <Jerry.Zhang@amd.com>
[v2: allow returning the first signaled fence index]
Signed-off-by: monk.liu <Monk.Liu@amd.com>
[v3:
 - cleanup *status setting
 - fix amdgpu symbols check
v4: simplify return from amdgpu_cs_wait_fences (suggested
    by Edward O'Callaghan)]
Signed-off-by: Nicolai Hähnle <nicolai.haehnle@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com> (v1)
Reviewed-by: Jammy Zhou <Jammy.Zhou@amd.com> (v1)
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>