msm: kgsl: set the dma_address field of scatterlists

Ion carveout and content protect heap buffers do not
have a struct page associated with them. Thus
sg_phys() will not work reliably on these buffers.
Set the dma_address field on physically contiguous
buffers.  When mapping a scatterlist to the gpummu
use sg_dma_address() first and if it returns 0
then use sg_phys().

Change-Id: Ie5f19986446be4383dfbfffa2534136b592e8e46
Signed-off-by: Jeremy Gebben <jgebben@codeaurora.org>