arm64: dma: Bring back set_dma_ops

Add the set_dma_ops function for arm64. It will be used by dma-removed.c.

Change-Id: I315547fcaed80d0424ab8fc920b95d79cfcebdc5
Signed-off-by: Rohit Vaswani <rvaswani@codeaurora.org>
Signed-off-by: Patrick Daly <pdaly@codeaurora.org>