msm: kgsl: Handle fence_add_callback error correctly

The function fence_add_callback returns error if the fence
has already signaled. Handle it correctly in kgsl and do
not propagate this to userspace.

Change-Id: Iabc50b271f1d834c9763eb00d1d296f2b19fbbcd
Signed-off-by: Harshdeep Dhatt <hdhatt@codeaurora.org>
diff --git a/drivers/gpu/msm/kgsl_sync.c b/drivers/gpu/msm/kgsl_sync.c
index 3b57b73..7701395 100644
--- a/drivers/gpu/msm/kgsl_sync.c
+++ b/drivers/gpu/msm/kgsl_sync.c
@@ -447,7 +447,7 @@
 
 	if (status) {
 		kfree(kcb);
-		if (fence_is_signaled(fence))
+		if (!fence_is_signaled(fence))
 			kcb = ERR_PTR(status);
 		else
 			kcb = NULL;