crypto: ixp4xx - Use sg_virt()

Use sg_virt() instead of open-coding it.
Signed-off-by: NGeliang Tang <geliangtang@gmail.com>
Acked-by: NDavid S. Miller <davem@davemloft.net>
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>

drivers/crypto/ixp4xx_crypto.c

@@ -806,7 +806,7 @@ static struct buffer_desc *chainup_buffers(struct device *dev,
 		void *ptr;
 
 		nbytes -= len;
-		ptr = page_address(sg_page(sg)) + sg->offset;
+		ptr = sg_virt(sg);
 		next_buf = dma_pool_alloc(buffer_pool, flags, &next_buf_phys);
 		if (!next_buf) {
 			buf = NULL;