dma-remap: drop nth_page() in dma_common_contiguous_remap()

dma_common_contiguous_remap() is used to remap an "allocated contiguous
region". Within a single allocation, there is no need to use nth_page()
anymore.

Neither the buddy, nor hugetlb, nor CMA will hand out problematic page
ranges.

Link: https://lkml.kernel.org/r/[e-mail]
Signed-off-by: David Hildenbrand <[e-mail]>
Acked-by: Marek Szyprowski <[e-mail]>
Reviewed-by: Lorenzo Stoakes <[e-mail]>
Cc: Robin Murphy <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>

kernel/dma/remap.c

···
 	if (!pages)
 		return NULL;
 	for (i = 0; i < count; i++)
-		pages[i] = nth_page(page, i);
+		pages[i] = page++;
 	vaddr = vmap(pages, count, VM_DMA_COHERENT, prot);
 	kvfree(pages);