serial: imx: make sure unhandled irqs are disabled

	temp |= (UCR2_RXEN | UCR2_TXEN);

	if (!sport->have_rtscts)

		temp |= UCR2_IRTS;

	/*

	 * make sure the edge sensitive RTS-irq is disabled,

	 * we're using RTSD instead.

	 */

	if (!is_imx1_uart(sport))

		temp &= ~UCR2_RTSEN;

	writel(temp, sport->port.membase + UCR2);

	if (!is_imx1_uart(sport)) {

		temp = readl(sport->port.membase + UCR3);

		temp |= IMX21_UCR3_RXDMUXSEL | UCR3_ADNIMP;

		/*

		 * The effect of RI and DCD differs depending on the UFCR_DCEDTE

		 * bit. In DCE mode they control the outputs, in DTE mode they

		 * enable the respective irqs. At least the DCD irq cannot be

		 * cleared on i.MX25 at least, so it's not usable and must be

		 * disabled. I don't have test hardware to check if RI has the

		 * same problem but I consider this likely so it's disabled for

		 * now, too.

		 */

		temp |= IMX21_UCR3_RXDMUXSEL | UCR3_ADNIMP |

			UCR3_RI | UCR3_DCD;

		if (sport->dte_mode)

			temp &= ~(UCR3_RI | UCR3_DCD);

		writel(temp, sport->port.membase + UCR3);

	}