kernel/dma: remove unsupported gfp_mask parameter from dma_alloc_from_contiguous()

The CMA memory allocator doesn't support standard gfp flags for memory
allocation, so there is no point having it as a parameter for
dma_alloc_from_contiguous() function.  Replace it by a boolean no_warn
argument, which covers all the underlaying cma_alloc() function
supports.

This will help to avoid giving false feeling that this function supports
standard gfp flags and callers can pass __GFP_ZERO to get zeroed buffer,
what has already been an issue: see commit dd65a941f6 ("arm64:
dma-mapping: clear buffers allocated with FORCE_CONTIGUOUS flag").

Link: http://lkml.kernel.org/r/20180709122020eucas1p21a71b092975cb4a3b9954ffc63f699d1~-sqUFoa-h2939329393eucas1p2Y@eucas1p2.samsung.com
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Acked-by: Michał Nazarewicz <mina86@mina86.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Laura Abbott <labbott@redhat.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Joonsoo Kim <js1304@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/arm64/mm/dma-mapping.c

@@ -355,7 +355,7 @@ static int __init atomic_pool_init(void)
 
 	if (dev_get_cma_area(NULL))
 		page = dma_alloc_from_contiguous(NULL, nr_pages,
-						 pool_size_order, GFP_KERNEL);
+						 pool_size_order, false);
 	else
 		page = alloc_pages(GFP_DMA32, pool_size_order);
 
@@ -573,7 +573,7 @@ static void *__iommu_alloc_attrs(struct device *dev, size_t size,
 		struct page *page;
 
 		page = dma_alloc_from_contiguous(dev, size >> PAGE_SHIFT,
-						 get_order(size), gfp);
+					get_order(size), gfp & __GFP_NOWARN);
 		if (!page)
 			return NULL;