tty: serial: st-asc: Make the locking RT aware

The lock is a sleeping lock and local_irq_save() is not the
standard implementation now. Working for both -RT and non
RT.
Signed-off-by: Lionel Debieve <lionel.debieve@st.com>
Acked-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Acked-by: Patrice Chotard <patrice.chotard@st.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/st-asc.c

@@ -887,13 +887,12 @@ static void asc_console_write(struct console *co, const char *s, unsigned count)
 	int locked = 1;
 	u32 intenable;
 
-	local_irq_save(flags);
 	if (port->sysrq)
 		locked = 0; /* asc_interrupt has already claimed the lock */
 	else if (oops_in_progress)
-		locked = spin_trylock(&port->lock);
+		locked = spin_trylock_irqsave(&port->lock, flags);
 	else
-		spin_lock(&port->lock);
+		spin_lock_irqsave(&port->lock, flags);
 
 	/*
 	 * Disable interrupts so we don't get the IRQ line bouncing
@@ -911,8 +910,7 @@ static void asc_console_write(struct console *co, const char *s, unsigned count)
 	asc_out(port, ASC_INTEN, intenable);
 
 	if (locked)
-		spin_unlock(&port->lock);
-	local_irq_restore(flags);
+		spin_unlock_irqrestore(&port->lock, flags);
 }
 
 static int asc_console_setup(struct console *co, char *options)