gpio-button-hotplug: use gpio_button_get_value() to initialize last_state.

TL-WR720N-v3 has a slider switch composed of 2 GPIO buttons which can be
used to swtich between 3 positions.  At leat 1 button is in pressed state
in any of those positions.  Initialize 'last_state' as 0 (released) will
cause the device to automatically enter failsafe mode on every bootup.

Signed-off-by: Yousong Zhou <yszhou4tech@gmail.com>

SVN-Revision: 37643

package/kernel/gpio-button-hotplug/src/gpio-button-hotplug.c

@@ -509,7 +509,7 @@ static int gpio_keys_polled_probe(struct platform_device *pdev)
 		}
 
 		bdata->can_sleep = gpio_cansleep(gpio);
-		bdata->last_state = 0;
+		bdata->last_state = gpio_button_get_value(button, bdata);
 		bdata->threshold = DIV_ROUND_UP(button->debounce_interval,
 						pdata->poll_interval);
 	}