drm/amdgpu/sdma: fix mask in emit_pipeline_sync

commit 4a8e06f7aad797e92413a3042d09d3b385fa1fda upstream.

Needs to be a 32 bit mask.

Acked-by: Huang Rui <ray.huang@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>