blackpill: Use bootloader LED macro to control LEDs

The LED used to indicate the bootloader is active
is selected according to whether the bootloader
was built for Blackpill-F4 on carrier or standalone.

src/platforms/common/blackpill-f4/usbdfu.c

@@ -121,12 +121,12 @@ void sys_tick_handler(void)
 	case 0U:
 		/* Reload downcounter and disable LED */
 		count = 10U;
-		SET_IDLE_STATE(false);
+		SET_BOOTLOADER_STATE(false);
 		break;
 	case 1U:
 		count--;
 		/* Enable LED for 1/10th of cycle */
-		SET_IDLE_STATE(true);
+		SET_BOOTLOADER_STATE(true);
 		break;
 	default:
 		count--;