drm/msm/sde: trigger fence from sde_fence_create API

SDE driver triggers the retire fence from "crtc_event"
thread and client may request the new fence in
"client_thread". It is possible that "crtc_event" thread
schedule first and tries to trigger the pending fence.
It won't be able to signal any fence because client thread
is not scheduled yet and it has not added any fence in
fence list. This race condition can be avoided by signaling
the fence from both APIs.

Change-Id: Ide5a0789ee3a880de0c1934b67591126e4e6a100
Signed-off-by: Dhaval Patel <pdhaval@codeaurora.org>