synx: Add synx cancel signaling status

Add cancel signaling status for the synx object. This
can be used by the clients to signal cancellation to
other clients waiting on the synx object and helps
distinguish from any error occurred during signaling.

Change-Id: Idba21d364c2306ef65d53ae6728da8a49131605d
Signed-off-by: Sumukh Hallymysore Ravindra <shallymy@codeaurora.org>