lights: There are no buttons here

Change-Id: I53506ff5e72ec63b66d6873ad142803dd5848238

liblight/lights.c

@@ -52,9 +52,6 @@ char const*const BLUE_LED_FILE
 char const*const LCD_FILE
         = "/sys/class/leds/lcd-backlight/brightness";
 
-char const*const BUTTON_FILE
-        = "/sys/class/leds/button-backlight/brightness";
-
 char const*const RED_BLINK_FILE
         = "/sys/class/leds/red/blink";
 
@@ -249,20 +246,6 @@ set_light_attention(struct light_device_t* dev,
     return 0;
 }
 
-static int
-set_light_buttons(struct light_device_t* dev,
-        struct light_state_t const* state)
-{
-    int err = 0;
-    if(!dev) {
-        return -1;
-    }
-    pthread_mutex_lock(&g_lock);
-    err = write_int(BUTTON_FILE, state->color & 0xFF);
-    pthread_mutex_unlock(&g_lock);
-    return err;
-}
-
 /** Close the lights device */
 static int
 close_lights(struct light_device_t *dev)
@@ -293,8 +276,6 @@ static int open_lights(const struct hw_module_t* module, char const* name,
         set_light = set_light_battery;
     else if (0 == strcmp(LIGHT_ID_NOTIFICATIONS, name))
         set_light = set_light_notifications;
-    else if (0 == strcmp(LIGHT_ID_BUTTONS, name))
-        set_light = set_light_buttons;
     else if (0 == strcmp(LIGHT_ID_ATTENTION, name))
         set_light = set_light_attention;
     else