cris: fix a build error in drivers/tty/serial/crisv10.c

This patch fixes the following build error:

drivers/tty/serial/crisv10.c:4453: error: 'if_ser0' undeclared (first use in this function): 2 errors in 2 logs
        v3.1-rc4/cris/cris-allmodconfig v3.1-rc4/cris/cris-allyesconfig
drivers/tty/serial/crisv10.c:4453: error: (Each undeclared identifier is reported only once: 2 errors in 2 logs
        v3.1-rc4/cris/cris-allmodconfig v3.1-rc4/cris/cris-allyesconfig
drivers/tty/serial/crisv10.c:4453: error: for each function it appears in.): 2 errors in 2 logs
        v3.1-rc4/cris/cris-allmodconfig v3.1-rc4/cris/cris-allyesconfig

"if_ser0" is a typo, it should be "if_serial_0".

Cc: Mikael Starvik <starvik@axis.com>
Cc: Jesper Nilsson <jesper.nilsson@axis.com>
Signed-off-by: WANG Cong <xiyou.wangcong@gmail.com>
Cc: stable <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/tty/serial/crisv10.c

@@ -4450,7 +4450,7 @@ static int __init rs_init(void)
 
 #if defined(CONFIG_ETRAX_RS485)
 #if defined(CONFIG_ETRAX_RS485_ON_PA)
-	if (cris_io_interface_allocate_pins(if_ser0, 'a', rs485_pa_bit,
+	if (cris_io_interface_allocate_pins(if_serial_0, 'a', rs485_pa_bit,
 			rs485_pa_bit)) {
 		printk(KERN_CRIT "ETRAX100LX serial: Could not allocate "
 			"RS485 pin\n");
@@ -4459,7 +4459,7 @@ static int __init rs_init(void)
 	}
 #endif
 #if defined(CONFIG_ETRAX_RS485_ON_PORT_G)
-	if (cris_io_interface_allocate_pins(if_ser0, 'g', rs485_pa_bit,
+	if (cris_io_interface_allocate_pins(if_serial_0, 'g', rs485_pa_bit,
 			rs485_port_g_bit)) {
 		printk(KERN_CRIT "ETRAX100LX serial: Could not allocate "
 			"RS485 pin\n");