dma-buf/fence: fix fence_is_later v2

A fence is never later than itself. This caused a bunch of overhead for AMDGPU.

v2: simplify check as suggested by Michel.
Signed-off-by: NChristian König <christian.koenig@amd.com>
Reviewed-by: NMichel Dänzer <michel.daenzer@amd.com>
Reviewed-by: NAlex Deucher <alexander.deucher@amd.com>
Reviewed-by: NGustavo Padovan <gustavo.padovan@collabora.co.uk>
Reviewed-by: NMaarten Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>
Signed-off-by: NSumit Semwal <sumit.semwal@linaro.org>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

include/linux/fence.h

@@ -292,7 +292,7 @@ static inline bool fence_is_later(struct fence *f1, struct fence *f2)
 	if (WARN_ON(f1->context != f2->context))
 		return false;
 
-	return f1->seqno - f2->seqno < INT_MAX;
+	return (int)(f1->seqno - f2->seqno) > 0;
 }
 
 /**