drm/amdgpu: suspend ras module before gpu reset

drm/amdgpu: suspend ras module before gpu reset

During gpu reset, all GPU-related resources are
inaccessible. To avoid affecting ras functionality,
suspend ras module before gpu reset and resume
it after gpu reset is complete.

V2:
  Rename functions to avoid misunderstanding.

V3:
  Move flush_delayed_work to amdgpu_ras_process_pause,
  Move schedule_delayed_work to amdgpu_ras_process_unpause.

V4:
  Rename functions.

V5:
  Move the function to amdgpu_ras.c.

Signed-off-by: YiPeng Chai <YiPeng.Chai@amd.com>
Reviewed-by: Tao Zhou <tao.zhou1@amd.com>
Reviewed-by: Hawking Zhang <Hawking.Zhang@amd.com>
Acked-by: Lijo Lazar <lijo.lazar@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>