ARM: 8763/1: dma-mapping: Use vma_pages()

Use vma_pages() function instead of open coding it.

Generated by scripts/coccinelle/api/vma_pages.cocci.
Signed-off-by: NFabio Estevam <fabio.estevam@nxp.com>
Signed-off-by: NRussell King <rmk+kernel@armlinux.org.uk>

arch/arm/mm/dma-mapping.c

@@ -845,7 +845,7 @@ static int __arm_dma_mmap(struct device *dev, struct vm_area_struct *vma,
 		 unsigned long attrs)
 {
 	int ret;
-	unsigned long nr_vma_pages = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
+	unsigned long nr_vma_pages = vma_pages(vma);
 	unsigned long nr_pages = PAGE_ALIGN(size) >> PAGE_SHIFT;
 	unsigned long pfn = dma_to_pfn(dev, dma_addr);
 	unsigned long off = vma->vm_pgoff;