tty/serial: Fix XSCALE serial ports, e.g. ce4100

Commit 4539c24 "tty/serial: Add
explicit PORT_TEGRA type" introduced separate flags describing the need
for IER bits UUE and RTOIE. Both bits are required for the XSCALE port
type. While that patch updated uart_config[] as required, the auto-probing
code wasn't updated to set the RTOIE flag when an XSCALE port type was
detected. This caused such ports to stop working. This patch rectifies
that.

Reported-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Tested-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Stephen Warren <swarren@nvidia.com>
Cc: stable <stable@kernel.org> [3.0]
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/tty/serial/8250.c

@@ -1107,7 +1107,7 @@ static void autoconfig_16550a(struct uart_8250_port *up)
 			 */
 			DEBUG_AUTOCONF("Xscale ");
 			up->port.type = PORT_XSCALE;
-			up->capabilities |= UART_CAP_UUE;
+			up->capabilities |= UART_CAP_UUE | UART_CAP_RTOIE;
 			return;
 		}
 	} else {