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: Fabio Estevam <fabio.estevam@nxp.com>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>