drm/nouveau: remove trace_dma_fence_emit

Hardware drivers which don't have much difference between emit and init
shouldn't use this trace point.

Signed-off-by: Christian König <christian.koenig@amd.com>
Cc: Ben Skeggs <bskeggs@redhat.com>
Cc: Karol Herbst <kherbst@redhat.com>
Cc: Lyude Paul <lyude@redhat.com>
Cc: nouveau@lists.freedesktop.org
Reviewed-by: Lyude Paul <lyude@redhat.com>
Signed-off-by: Lyude Paul <lyude@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220503085935.11023-1-christian.koenig@amd.com