ARM: dma-mapping: don't allow DMA mappings to be marked executable

DMA mapping permissions were being derived from pgprot_kernel directly
without using PAGE_KERNEL.  This causes them to be marked with executable
permission, which is not what we want.  Fix this.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
static struct page **__atomic_get_pages(void *addr)
{
	struct dma_pool *pool = &atomic_pool;
	struct page **pages = pool->pages;
	int offs = (addr - pool->vaddr) >> PAGE_SHIFT;

	return pages + offs;
}

static struct page **__atomic_get_pages(void *addr)
{
	struct dma_pool *pool = &atomic_pool;
	struct page **pages = pool->pages;
	int offs = (addr - pool->vaddr) >> PAGE_SHIFT;

	return pages + offs;
}
