drm: expand drm_syncobj_find_fence to support timeline point v2

we can fetch timeline point fence after expanded.
v2: The parameter fence is the result of the function and should come last.

Signed-off-by: Chunming Zhou <david1.zhou@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Christian König <christian.koenig@amd.com>
Link: https://patchwork.freedesktop.org/patch/246541/


(cherry picked from commit 0a6730ea)
Signed-off-by: Eric Anholt <eric@anholt.net>