gpu: ion: ion_system_heap: Change allocations to GFP_HIGHUSER

Previously the ion_system_heap was using GFP_KERNEL, forcing all allocations
to be in lowmem.  This quickly causes us to run out of lowmem.
Signed-off-by: Rebecca Schultz Zavin <rebecca@android.com>
[jstultz: modified patch to apply to staging directory]
Signed-off-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/android/ion/ion_system_heap.c

@@ -40,7 +40,7 @@ static int ion_system_heap_allocate(struct ion_heap *heap,
 		goto err0;
 	for_each_sg(table->sgl, sg, table->nents, i) {
 		struct page *page;
-		page = alloc_page(GFP_KERNEL);
+		page = alloc_page(GFP_HIGHUSER | __GFP_ZERO);
 		if (!page)
 			goto err1;
 		sg_set_page(sg, page, PAGE_SIZE, 0);