dma/fence: Export enable-signaling tracepoint for emission by drivers

Currently this tracepoint is solely used by dma_fence_enable_sw_signaling,
however I have a need to manually perform the hw enabling of the
signaling and would like to emit this tracepoint for completeness.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Acked-by: NSumit Semwal <sumit.semwal@linaro.org>
Signed-off-by: NGustavo Padovan <gustavo.padovan@collabora.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170124115758.31353-1-chris@chris-wilson.co.uk

drivers/dma-buf/dma-fence.c

@@ -28,6 +28,7 @@
 
 EXPORT_TRACEPOINT_SYMBOL(dma_fence_annotate_wait_on);
 EXPORT_TRACEPOINT_SYMBOL(dma_fence_emit);
+EXPORT_TRACEPOINT_SYMBOL(dma_fence_enable_signal);
 
 /*
  * fence context counter: each execution context should have its own