This reverts commit 5de376bb.

This change breaks synchronization of a timeline.
dma_fence_chain_find_seqno() might be a bit of a confusing name but
this function is not trying to find a particular seqno, is supposed to
give a fence to wait on for a particular point in the timeline.

In a timeline, a particular value is reached when all the points up to
and including that value have signaled.
Signed-off-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Link: https://patchwork.freedesktop.org/patch/372958/Signed-off-by: Christian König <christian.koenig@amd.com>