ARM: 8551/2: DMA: Fix kzalloc flags in __dma_alloc

Commit 19e6e5e5 ("ARM: 8547/1: dma-mapping: store buffer
information") allocates a structure meant for internal buffer management
with the GFP flags of the buffer itself. This can trigger the following
safeguard in the slab/slub allocator:

	if (unlikely(flags & GFP_SLAB_BUG_MASK)) {
		pr_emerg("gfp: %un", flags & GFP_SLAB_BUG_MASK);
		BUG();
	}

Fix this by filtering the flags that make the slab allocator unhappy.
Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>
Acked-by: Rabin Vincent <rabin@rab.in>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

arch/arm/mm/dma-mapping.c

@@ -762,7 +762,8 @@ static void *__dma_alloc(struct device *dev, size_t size, dma_addr_t *handle,
 	if (!mask)
 		return NULL;
 
-	buf = kzalloc(sizeof(*buf), gfp);
+	buf = kzalloc(sizeof(*buf),
+		      gfp & ~(__GFP_DMA | __GFP_DMA32 | __GFP_HIGHMEM));
 	if (!buf)
 		return NULL;