msm: kgsl: Cleanup the fence if it cannot be added

If a callback cannot be registered for a fence, remove it from
the sync timeline. This avoids a memory leak if the fence is
not signaled.

Change-Id: I8ce8ba3ad6fd2fec90e2eb862f51fbac0167815d
Signed-off-by: Lynus Vaz <lvaz@codeaurora.org>