gpu: ion: Set the dma address for pages from the page pool

In order to properly call dma_sync_sg_for_device, the dma address
must be set on each scatterlist. When manually creating sg lists from
individual pages, the dma address must be set manually, else the cache
flushing will not succeed. Set the dma address of the sg list for
uncached page flushing to ensure the pages get completely flushed.

Change-Id: I1b89b5e2bd5ba75e7340c347eab256acec7d9554
CRs-Fixed: 496298
Signed-off-by: Laura Abbott <lauraa@codeaurora.org>