serial: pch_uart: use offset_in_page() macro

Use offset_in_page() macro instead of open-coding.
Signed-off-by: NGeliang Tang <geliangtang@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/pch_uart.c

@@ -878,8 +878,7 @@ static int dma_handle_rx(struct eg20t_port *priv)
 	sg_dma_len(sg) = priv->trigger_level;
 
 	sg_set_page(&priv->sg_rx, virt_to_page(priv->rx_buf_virt),
-		     sg_dma_len(sg), (unsigned long)priv->rx_buf_virt &
-		     ~PAGE_MASK);
+		     sg_dma_len(sg), offset_in_page(priv->rx_buf_virt));
 
 	sg_dma_address(sg) = priv->rx_buf_dma;