drm/radeon/kms: add cayman specific fence_ring_emit

cayman is wb only and doesn't have a VC.

Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Christian König <deathsimple@vodafone.de>
Signed-off-by: Dave Airlie <airlied@redhat.com>
4 files changed