drm/radeon: allow semaphore emission to fail

To workaround bugs and/or certain limits it's sometimes
useful to fall back to waiting on fences.

Signed-off-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org
17 files changed