ANDROID: goldfish_sync_timeline: Rename fence to dma_fence

Rename fence interfaces to dma_fence to match with the upstream
commit, f54d1867 ("dma-buf: Rename struct fence to dma_fence"),
changes.

FIXME: Might be a good idea to remove goldfish_sync_timeline and
       use upstream sync_timeline interfaces instead.

Signed-off-by: Amit Pundir <amit.pundir@linaro.org>