ANDROID: iommu/dma: Add support for DMA_ATTR_SYS_CACHE

IOMMU_SYS_CACHE allows buffers for non-coherent devices to be mapped
with the correct memory attributes so that the buffers can be cached
in the system cache. However, this property is only usable by drivers
that invoke the IOMMU API directly; it is not usable by drivers that
use the DMA API.

Thus, introduce DMA_ATTR_SYS_CACHE, so that drivers for non-coherent
devices that use the DMA API can use it to specify if they want a
buffer to be cached in the system cache.

Bug: 189339242
Change-Id: I849d7a3f36b689afd2f6ee400507223fd6395158
Signed-off-by: Isaac J. Manjarres <isaacm@codeaurora.org>
Signed-off-by: Georgi Djakov <quic_c_gdjako@quicinc.com>