s390/pci: return correct dma address for offset > PAGE_SIZE

For offset > PAGE_SIZE, s390_dma_map_pages() will issue a warning
and return a wrong dma address.

This patch removes the warning and fixes the dma return address
calculation.
Signed-off-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/pci/pci_dma.c

@@ -269,8 +269,6 @@ static dma_addr_t s390_dma_map_pages(struct device *dev, struct page *page,
 	int flags = ZPCI_PTE_VALID;
 	dma_addr_t dma_addr;
 
-	WARN_ON_ONCE(offset > PAGE_SIZE);
-
 	/* This rounds up number of pages based on size and offset */
 	nr_pages = iommu_num_pages(pa, size, PAGE_SIZE);
 	iommu_page_index = dma_alloc_iommu(zdev, nr_pages);
@@ -292,7 +290,7 @@ static dma_addr_t s390_dma_map_pages(struct device *dev, struct page *page,
 
 	if (!dma_update_trans(zdev, pa, dma_addr, size, flags)) {
 		atomic64_add(nr_pages, (atomic64_t *) &zdev->fmb->mapped_pages);
-		return dma_addr + offset;
+		return dma_addr + (offset & ~PAGE_MASK);
 	}
 
 out_free: