serial: sh-sci: prevent setup of uninitialized serial console

Commit 906b17dc introduced a condition
where the kernel will crash unless a earlyprintk parameter is specified.

Without this parameter, sci_console_init is called during early console
setup without any port being initialized, and the kernel crashes a
little bit later when uart_set_options attemps to invoke set_termios on a
port with an ops member equal to NULL.

This patch just checks in sci_console_init that the port is properly
initialized, and aborts the early console setup if it is not.
Signed-off-by: Alexandre Courbot <gnurou@gmail.com>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>

drivers/tty/serial/sh-sci.c

@@ -1836,6 +1836,12 @@ static int __devinit serial_console_setup(struct console *co, char *options)
 	sci_port = &sci_ports[co->index];
 	port = &sci_port->port;
 
+	/*
+	 * Refuse to handle uninitialized ports.
+	 */
+	if (!port->ops)
+		return -ENODEV;
+
 	ret = sci_remap_port(port);
 	if (unlikely(ret != 0))
 		return ret;