auxdisplay: make charlcd_backlight visible to hd44780_common

hd44780_common wants to use the charlcd_backlight function, so make it
visible.
Reviewed-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Lars Poeschel <poeschel@lemonage.de>
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>

drivers/auxdisplay/charlcd.c

@@ -91,7 +91,7 @@ static void long_sleep(int ms)
 }
 
 /* turn the backlight on or off */
-static void charlcd_backlight(struct charlcd *lcd, enum charlcd_onoff on)
+void charlcd_backlight(struct charlcd *lcd, enum charlcd_onoff on)
 {
 	struct charlcd_priv *priv = charlcd_to_priv(lcd);
 
@@ -103,6 +103,7 @@ static void charlcd_backlight(struct charlcd *lcd, enum charlcd_onoff on)
 		lcd->ops->backlight(lcd, on);
 	mutex_unlock(&priv->bl_tempo_lock);
 }
+EXPORT_SYMBOL_GPL(charlcd_backlight);
 
 static void charlcd_bl_off(struct work_struct *work)
 {

drivers/auxdisplay/charlcd.h

@@ -56,6 +56,7 @@ struct charlcd_ops {
 	int (*clear_display)(struct charlcd *lcd);
 };
 
+void charlcd_backlight(struct charlcd *lcd, enum charlcd_onoff on);
 struct charlcd *charlcd_alloc(void);
 void charlcd_free(struct charlcd *lcd);