ARM: dma-mapping: add support for DMA_ATTR_FORCE_CONTIGUOUS attribute

This patch adds support for DMA_ATTR_FORCE_CONTIGUOUS attribute for
dma_alloc_attrs() in IOMMU-aware implementation. For allocating physically
contiguous buffers Contiguous Memory Allocator is used.

Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>