drm/msm/sde: fix sde fence tracing and signal support

Update sde context structure before creating dma-buf
fence. The fence_init API may call the timeline name
get callback API if trace events are enabled. The change
also updates the fence eventlog in all cases and changes
the signal API.

Change-Id: Ibbfb514fc9165b21060b6d3a7aa0956501e6870a
Signed-off-by: Dhaval Patel <pdhaval@codeaurora.org>