serial: Take uart port lock for direct *_enable_ms()

Three UART drivers (8250, atmel & amba-pl010) directly call their
enable_ms() method; the uart port lock must be acquired before
any h/w programming.
Signed-off-by: NPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/8250/8250_core.c

@@ -2613,7 +2613,9 @@ serial8250_set_ldisc(struct uart_port *port, struct ktermios *termios)
 {
 	if (termios->c_line == N_PPS) {
 		port->flags |= UPF_HARDPPS_CD;
+		spin_lock_irq(&port->lock);
 		serial8250_enable_ms(port);
+		spin_unlock_irq(&port->lock);
 	} else
 		port->flags &= ~UPF_HARDPPS_CD;
 }

drivers/tty/serial/amba-pl010.c

@@ -483,7 +483,9 @@ static void pl010_set_ldisc(struct uart_port *port, struct ktermios *termios)
 {
 	if (termios->c_line == N_PPS) {
 		port->flags |= UPF_HARDPPS_CD;
+		spin_lock_irq(&port->lock);
 		pl010_enable_ms(port);
+		spin_unlock_irq(&port->lock);
 	} else
 		port->flags &= ~UPF_HARDPPS_CD;
 }

drivers/tty/serial/atmel_serial.c

@@ -2060,7 +2060,9 @@ static void atmel_set_ldisc(struct uart_port *port, struct ktermios *termios)
 {
 	if (termios->c_line == N_PPS) {
 		port->flags |= UPF_HARDPPS_CD;
+		spin_lock_irq(&port->lock);
 		atmel_enable_ms(port);
+		spin_unlock_irq(&port->lock);
 	} else {
 		port->flags &= ~UPF_HARDPPS_CD;
 	}