media: mediatek: vcodec: Alloc DMA memory with DMA_ATTR_ALLOC_SINGLE_PAGES

As talked about in commit 14d3ae2efeed ("ARM: 8507/1: dma-mapping: Use
DMA_ATTR_ALLOC_SINGLE_PAGES hint to optimize alloc"), it doesn't
really make sense to try to allocate contiguous chunks of memory for
video encoding/decoding. Let's switch the Mediatek vcodec driver to
pass DMA_ATTR_ALLOC_SINGLE_PAGES and take some of the stress off the
memory subsystem.

Signed-off-by: Douglas Anderson <[e-mail]>
Tested-by: Fei Shao <[e-mail]>
Reviewed-by: Fei Shao <[e-mail]>
Reviewed-by: Nicolas Dufresne <[e-mail]>
Signed-off-by: Sebastian Fricke <[e-mail]>
Signed-off-by: Hans Verkuil <[e-mail]>

drivers/media/platform/mediatek/vcodec/common/mtk_vcodec_util.c

···
 		id = dec_ctx->id;
 	}
 
-	mem->va = dma_alloc_coherent(&plat_dev->dev, mem->size, &mem->dma_addr, GFP_KERNEL);
+        mem->va = dma_alloc_attrs(&plat_dev->dev, mem->size, &mem->dma_addr,
+                                  GFP_KERNEL, DMA_ATTR_ALLOC_SINGLE_PAGES);
 	if (!mem->va) {
 		mtk_v4l2_err(plat_dev, "%s dma_alloc size=0x%zx failed!",
 			     __func__, mem->size);