serial: fix serial_txx9 console initialization

Since commit 97d97224ff361e08777fb33e0fd193ca877dac28 ("[SERIAL] Fix
console initialisation ordering"), serial_core calls ->pm() on
initialization even if the port was used for console.

This behaviour breaks serial_txx9 console since The serial_txx9 driver
initialize its port entirely on its ->pm() method if new state was 0.
This patch adds checking for oldstate value to fix this probelm.

Signed-off-by: Atsushi Nemoto <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

drivers/serial/serial_txx9.c

···
 serial_txx9_pm(struct uart_port *port, unsigned int state,
 	      unsigned int oldstate)
 {
-	if (state == 0)
+	/*
+	 * If oldstate was -1 this is called from
+	 * uart_configure_port().  In this case do not initialize the
+	 * port now, because the port was already initialized (for
+	 * non-console port) or should not be initialized here (for
+	 * console port).  If we initialized the port here we lose
+	 * serial console settings.
+	 */
+	if (state == 0 && oldstate != -1)
 		serial_txx9_initialize(port);
 }