arm64: Add dma mapping APIs for other memory types

Users of dma on arm may call dma_*_writecombine and dma_*_nonconsistent.
Add these functions for arm64 as well.

Change-Id: I213f8314022969bcefbfcd8581725762c385fb18
Signed-off-by: Laura Abbott <lauraa@codeaurora.org>
Signed-off-by: Patrick Daly <pdaly@codeaurora.org>